I’ve featured Seikos 6139-600x series chronographs before but never a blue dialled one! I thought this may be of interest as it’s suffered from quite a common problem whereby the minute counter doesn’t count or reset properly. This example came in needing a service and the minute register problem sorting. The photographs I took at the start didn’t come out for some reason (I think I probably deleted them by pressing the wrong button!) so we’ll start with the caseback removed. The movement looks in reasonable shape but the trace on the timegrapher was appalling so it was definitely in need of a service

As you can see the dial and handset are in cracking condition apart from a little paint loss on the minute registers hand.

With the dial and hand removed the day/date rings are now visible.

The stripdown goes without any issues, here the keyless work is exposed. Note the return spring that bends around the top of the movement to facilitate the push day/date quickset.

The calendar side is fully stripped here.

With the movement turned over the autowind bridge is removed.

With the chronograph bridge removed the offending minute wheel was removed. These have a habit of coming apart like this, the pinion and wheel should be one unit.

They can be staked back together again but as I had some NOS ones in stock I used one of those. I tend to collect a few of these broken ones then stake them when I have the machine set up.

The rest of the stripdown was uneventful with just some evidence of dried out lubricants.

Soon it was ready for the cleaning machine and subsequent inspection.

Whilst the parts were spinning I turned my attention to the case. The pushers were removed and the tubes were found to be chock full of what looked like dried mud!

There was quite a bit of gunk in there….

….and the pushers also had no o-rings fitted – not a good idea.

The case, pushers and springs were soon cleaned up and a new set of seals were fitted

The parts were removed from the cleaner and inspected.

The rebuild started with the mainspring….

….then the train….

The bridges are back on and she’s ticking away once more.

The calendar side was tackled next.

Ready for the top plate.

The dial and handset was refitted, the paint damaged minute register hand was replaced with a NOS one.

The movement was recased, this example sports a Dainiseikosha signed rotor.

The caseback was refitted….

…. which meant it was now all done. I do enjoy working on Seikos calibre 6139 & 8’s, a fabulously designed movement.