One of the defining features of my time as a casual practitioner of watchsmithery, independent of the trajectory my tastes have otherwise followed, has been a somewhat conflicted relationship with that most iconic of all Seiko divers watches, the second generation 6105.   To a large extent this derives from the fact that my first watch purchase as an object of desire rather than means to an end, was a 6105-8110 from November 1976. It also formed the basis of my first tentative steps towards watch fettling (an account of my first date wheel swap can be found somewhere still on Watchuseek) an activity that now occupies a great deal of my spare time. However, while I feel great affection for this particular model, it is a watch that I have struggled to get comfortable with, something to do with a combination of its 44 mm diameter combined with the architecture on its underside not quite fitting with the boney landscape of my upper wrist and compounded by the fact that I never seemed to be able to find a strap compliant enough or whose holes were quite in the right place. As a result, I’ve tended to favour the first generation 6105 whose smaller case somehow works a bit better for me. Nevertheless, I have persisted with this watch, not least because I like it so much as an aesthetic object.

The enduring appeal of the second generation 6105-8110/9 derives from a combination of its curvy, asymmetric cushion case, with its 6-slotted locking crown nestling in the gentle curve of the crown-guard just below a cusp that sees the case edge sweeping back in-land at the 3 o’clock position.

The dial, common to both generations of the watch, is another feature that sets it apart from later incarnations of the Seiko 150 m diver’s staple. The hour markers on the 6105 feature perfect, flat-topped borders generously filled with slightly off-white luminous compound.  On some 6105 dials, the markers appear to have been embossed through from the rear, whilst other, possibly later, dials have a rear free from the embossed indents, suggesting the markers are applied. However, from the front, on both types of dials, the markers emerge seamlessly from the black dial with no suggestion that they are simply glued to the surface. For this reason, there is a genuine sense of quality to the execution of the dial completely at odds with its position within the marketplace at the time.

The hands too are a vital component in the sum of parts that makes this such a wonderful watch. The hour and minute hands with their rectangular profile and beveled edges carry forward from the earlier 62MAS but the seconds hand sports a lovely playful design feature in the traffic light red dot sitting inboard of the main lumed hole at the end of the hand.

And finally, we have the coin-edge bezel,

filled with a perfectly executed slightly grained black insert, the lume pip sitting within an inverted triangle at its top, protected by a circular acrylic window.

Together these parts work to define a very Japanese watch, confident in its own design language with no sense at all that it has taken inspiration from elsewhere.  In some ways this watch marks the zenith in classic Japanese watchmaking of that period, before the industry as a whole became overrun by the quartz revolution.

One of the singular hazards in finding decent examples of this watch are the numerous examples in the market place that are saddled with dire after-market dials, shiny, poorly executed reproduction handsets and terrible, ill-fitting bezel inserts. While there are strategies that one can take to minimize the impact of the latter two, if you are to gain lasting enjoyment from this watch, you must, absolutely must buy one with the best possible quality original dial. If the dial is aftermarket, don’t give it a second thought. Walk on and keep looking.

I’ve had, I think, six or seven 6105’s over the years, all but two of which second generation examples. I learned my lesson on the dial front with the first but my desire since, to find watches with the best possible dials, has been tempered somewhat by my natural inclination to secure the best possible bargain and as a result, I’ve tended to buy tatty original examples needing some cosmetic attention to get the dial in respectable shape. Consequently, of the four 6105’s I currently own, three of them have been relumed, one of which by me and the other two by professional relumers. Nevertheless, I have continued on my quest to find an example with a perfect original dial and a little over 2 years ago, I found one. It has sat since in my to-do box waiting for its number to come up, which last month, it did.

Let’s get cracking then. Here it is, in the condition received:

You should be able to appreciate straightaway that the dial is a peach, the handset pretty good, particularly the traffic light seconds hand, and that the original bezel insert is largely unmarked, a considerable feat given that the crystal looks every one of its 41 years.

I am pretty sure that the crystal is original to the watch, its higher profile serving to protect the insert from day to day knocks.  While the exterior looks pretty presentable, the movement looks rather sorry for itself:

It is grubby as hell and looks to have been the subject of some rough handling but the good news is there is no sign of water ingress which means we should have the basis of a decent rebuild assuming the main plate is sound. Extracting the movement and turning it over confirms just how wonderful the dial is:

It is just about perfect. I can see no flaws or marks anywhere on its surface, the markers are completely free from corrosion or wear of any kind and the lume a perfect, slightly cream colour that heightens the vintage aesthetic. The lume on the minute hand, however, does show some discoloring and I think will need some attention if it is to be allowed to continue to keep company with the pristine dial.

For those of you still getting your eyes in as to what constitutes a decent 6105, compare and contrast the photo above with the aftermarket abomination shown here:  Accept no substitutes.

Moving swiftly on, a quick look at the reverse of the dial, now removed, reveals it to have had its hour markers punched through from the rear:

whilst the calendar side of the movement looks sound if, again, a little tarnished.

With the dial and handset set safely to one side, let’s get back to the flip side, both literally and metaphorically. Pretty much as soon as I received the watch back in late 2012, I knew that the movement needed work, first and foremost because the hairspring had obviously come in for some abuse.

It is not so difficult to imagine how someone cack of hand might inflict such damage but I do wonder what might have prompted them to open up the watch in the first place.  Removing the discoloured and scarred winding weight together with the autowinding mechanism exposes the train wheel bridge which looks ok.

but curiously I can see no sign of the third or fourth wheel arbors peeking through the holes in their respective bearings which makes me wonder whether the train wheel bridge had been fastened down without the train wheels properly engaged. Removing the train wheel bridge appears to confirm this as the third and fourth wheels come away with the bridge, glued in place by congealed oil.

The train wheels extracted and my fears are confirmed: at least one of the bearings on the bridge show significant signs of damage caused by the bridge being repeatedly screwed down with the third wheel arbor not having been properly engaged with its bearing hole. I fear the bridge too is a right-off.

The remainder of the movement looks dirty but otherwise ok.

As this is the later B variant of the 6105, we get a stop second facility and you can see the hacking lever in position in the photo above, its action working directly on the balance wheel rather than on the fourth wheel in the higher level 62xx series documented elsewhere.

As a final testament to its general grottiness, here’s a shot of the pallet fork jewels, both of which encrusted in congealed lubricant:

Now, what are we going to do about that knackered balance and vandalized train wheel bridge? Well, I am in the habit of acquiring bits and pieces for rainy days, and one such acquisition from ages ago was a new old stock 6106-7739 fitted with a 17 jewel hacking 6106C whose train wheel wheel bridge and balance are drop-in replacements of those in the 6105B.

Here’s the 6106C balance (left) next to the ruined balance from the 6105B:

The extracted bridge and balance from the 6106, together its train wheels join the rest of the disassembled 6105B in the ultrasonic bath and with everything cleaned, rinsed and dried, reassembly of the movement proceeded without further incident or upset (starting top right, proceeding anticlockwise):

In keeping with my intention of returning as much as possible of its original 1974 youthful vigour, I have also chosen to fit the barrel and mainspring from the 6106 donor.  Next, we need to figure out what to do with the hands.

The minute hand in particular looks a bit rough but rather than choosing to relume the original hands, I opt instead to relume a pair of identical Seiko hands taken from a 6119 dress watch using the originals as a colour guide. The seconds hand is in excellent shape and so I leave that be. Here’s my first attempt to get the lume colour right:

Perhaps a touch too much yellow and so with a second, paler batch made up, I relume the replacement hands

and leave to dry over night. I reckon the colour match is pretty good

and so we are set to refit the dial spacer to the movement

followed by the dial and hands:

It’s all pretty much down hill from here, just the relative drudgery of breaking down and cleaning the case parts and fitting a fresh crystal. The case is as typically dirty as we expect of used but not pampered watches. The area around the crown tube is a bit grim but happily we can make out the presence of the locking pin, only bearing relatively minor signs of wear

The bezel levers off to expose the crystal retaining ring, helpfully equipped with a strategically positioned slot to aid removal

I tend to remove these by working a thin blade around the whole circumference before levering off. It is not uncommon for the retaining rings to be cracked or corroded and a heavy handed removal can damage them.

At this point, we can push the crystal out from beneath and then extract the bezel gasket and rehaut. The mid case itself comprises 8 separate components

The case (centre) surrounded by the crystal (top) and then working anticlockwise, the crystal retaining ring, the L-shaped bezel gasket, the rehaut, movement ring, case back and turning ring with insert. As is common with watches of this age, a ninth component, the caseback gasket is hard and brittle and in clear need of replacement:

With the case cleaned, fit first the rehaut, followed by a fresh crystal gasket

The original gasket was very dirty and hardening where it had been exposed to the elements and so unusually I felt a replacement in order

For the crystal, I elected to go for a tempered mineral facsimile of the later, lower profile double domed service replacements. You can see its shallower aspect from this comparison with the original:

and here it is fitted to the case

and now held firm with the retaining ring back in position

Well, I think we are now set to re-case the movement, having first replaced the crown with a new old stock item, whose gasket is still sufficiently supple to restore water resistance

It is my habit to fit the movement first and see that everything runs happily before refitting the autowinder, the case at that point providing a sturdy support for the procedure. The autowinder framework needs reassembling from the sum of its parts first

before reuniting with the rest of the movement

The rotor from the 6106C donor movement tops things off

and with a fresh case back gasket, we can close her up and take a look from the dial side.

Somehow I find these views before the turning ring goes back on strangely appealing. The last step then is to clean up the turning ring

fit a fresh gasket, refit, locate a suitable strap and we are there

All that remains is to try out the new strap for comfort (a very nicely executed 731 reproduction from WJean)

and finish with a few closing shots:

As sequels go, the second generation 6105 has clearly eclipsed its older sibling in the consciousness of watch collectors. It is a watch of considerable charisma, certainly iconic in its way, but for me the greater subtlety of the earlier edition just about wins the day. To set my perspective in the context of its immediate predecessors, here’s a concluding view of the refreshed second generation 6105 (right), with the first gen (centre) and the watch that started the ball rolling, the 62MAS (left).