Well, its been about 2 months since I've aquired my Mark XI. I love the watch dearly, but it has started to lose time. (I waited about 6 weeks before taking timing measurements seriously, because it takes around that long for the movement to “settle” and all the lubricants to evenly distribute themselves).

I don't mind if my watch is a little off, but by this time, it was off by between 20-40 seconds a day, which can very quickly add up to a noticable discrepency. It always bothered me that I was never very sure of the time. The original MoD regulations specified that a Mark XI should exhibited a daily rate of no more than ±15 seconds and a daily variation of less than ±4 seconds.

At the moment, I'm shopping around for a watchmaker to restore my Mark XI. I'd like to have the hands cleaned up a bit, and possibly relumed. I really dislike how the radium painter coloured “outside the lines” on my the dial. (You can see this here.) I originally thought that this watch had endured a badly done re-dial, but as it turns out, this was simply a case of a badly done original MoD re-dial.

So, at any rate, at this point, I'm thinking about having a new dial fabricated, or possibly locating another JLC Mark XI dial, and having that re-painted. This way, I can keep the original dial in the event that I ever want to switch back to the original dial.

In the meantime, I've decided to try to regulate my watch to make it go a little faster. I'm very inexperienced at this sort of thing, but I reason that watches are probably like computers - they're incredibly complex, but the key is having enough confidence to experiment.

I'm pretty confident that I'll regret doing such rash things things in the future...

Before attempting to open the watch up, I put a cleaning cloth between the wrench and the case to act as “protective layer”. Most likely, this scheme better protects my conscience than the watch case.

I feel a bit like a magician - putting a cloth over the watch - can't see what I'm doing. “Now you see it, now you don't!”

Here, you can see what's on the inside of the caseback. The inside of the caseback has a nice circular brushed finish, just like the outside. The engraving reads “STAYBRITE / LeCoultre Co. / SWISS”.

The movement, which is not visible in this picture, is protected by a soft iron dust cover. “Dust cover” is a bit of a misnomer, because it shields the movement from magnetic fields (rotating magnetic fields are present in propeller aircraft) more than it protects against dust. The engraving on the dust cover reads “LIFT HERE”.

Staybrite refers to a type of stainless steel containing 12% chromium.
Paul Shepard: The bonklips were marked staybrite as well.

Here's the money shot! To my untrained eyes, the movement seems very nicely finished. (Sorry, this is about the most zoom my camera can do.)

The geneva stripes are very fine, and I can barely see the details of the finishing without aid of a loupe. All of the edges of the top plates are bevelled (I believe they call this anglage) and all the screws are polished. I read once that polished screws used to be the norm until sometime in the 80s/90s, when heat-blued screws became the convention of an aesthetically pleasing movement. Polished screws are more difficult to manufacture.

The main plate (you can see under the balance, and near the crown) is beautifully perlaged. On my watch, there are some very light scratches on the top plates, and a couple of nicks near the regulator. No real damage, but it's obvious that I'm not the first one to operate on this watch.

Here's a shot of the movement, with the balance wheel stopped. The balance was stopped by pulling out the crown which enacted the hack lever (1). To pull out the crown, I had to replace the dust cover which I'd removed earlier, because without it, the movement is loose inside the case, and you don't have enough leverage to pull out/manipulate the crown. (Note that the crown can be removed by undoing the crown release (4).)

I think the hack lever is a pretty interesting part of this movement - I've heard it described as “arcane” before. The lever actually pushes against the balance wheel directly (!), effectively freezing it in place.

The topmost gear/wheel (2) is the 3rd wheel in the power train. It sits between the center wheel (which carries the minute hand) and the 4th wheel (which acts on the seconds hand). It rotates once every 7.5 minutes.

The copper coloured strip in the center of the movement is the friction spring. There have been reports of some cal 488's that have a skipping sweep second hand (similar to the jump of a quartz watch's second hand). In many cases, it is not too difficult to correct this behaviour by bending the spring to ensure good contact. The spring can be extracted from the movement (so that you can bend it back into shape) by removing the screw that holds the spring.

To actually adjust the watch to go faster, I gently pushed the regulator (3) with a piece of pegwood towards “F”. (F=Faster, S=Slower, A=Avance, R=Retard) (The “S” is hidden under the regulator in this photo.) When I adjusted the watch, the balance was in motion. I reasoned that just like shipping a watch, leaving the balance in motion protects against bumps and shocks by providing a little inertia. Also, if the hack mechanism was engaged, the balance wheel would not be free to move in reaction to the regulator, putting undue stress on the Breguet spring.

I actually pushed the regulator a bit further than I meant to, but seeing as I didn't have any strong idea of how much it should go, I left it be. Time to pack it up and time it for a few days!

... 2 days later ...

After timing the Mark XI over 48 hours, it seems it ranges between 10 and 30 seconds slow a day, so we have some improvement! I'll open it up, and try the same trick again.

... 3 days later ...

Turns out, it's between 10 seconds fast, and 10 seconds slow - Good enough for me! I pronounce the operation a success! This should hold me over until I can have a real watchmaker take a look.