Here we have the little sister to the Tissot Seastar Automatic I serviced earlier this year.
When I picked up this piece it was, like many of the rest, in worn condition although it did run and the crown and crystal were still intact. Even better, this watch came with the original bracelet attached which although a little loose, was in fine shape. As usual there was a thick crust of grime and multiple scuffs and scratches which I’m sure deterred other potential buyers, but since I was in the market for another fully featured Women’s automatic I quickly closed the deal.
Unfortunately I discovered quite quickly that I received a bit more than I had bargained for. The caseback, which is a screw-on for a watertight seal, would not under any coaxing decouple from the case. I tried multiple dies, the application of heat, penetrating oil, and even harsh language without any luck. Finally I gave up and stowed the watch away until such time as further inspiration would strike. In the meantime I moved on to other projects.
Fortune would have it that I needed to visit a professional watchmaker for a large pocket watch project I had taken on. The watchmaker had graciously assisted by replacing the mainspring for the watch as I did not have a tool capable of taming the large Elgin mainspring. I brought along the Tissot in the off chance he had the tools and skill necessary to remove the caseback. It didn’t take long for him to have it loose and I was on my way.
Back in the workshop I carefully set about examining the movement for uglies before breaking it down. Right off the bat it was apparent that a full service would be required as the rubber caseback gasket had turned brittle and shattered when the case was opened. Tiny fragments of hardened rubber were now distributed throughout the movement.
Close examination of the movement revealed it to be a Tissot calibre 746 which was produced primarily in the late sixties and early seventies (pretty much the same time period as the Men’s Tissot I serviced earlier).
The movement is fully automatic as one would expect of a movement produced just prior to the Quartz watch revolution. Typically during an automatic watch service I’ll remove the rotor before extracting the movement from the case and this watch was no exception.
The autowinding mechanism is secured to the movement with two blued screws (one being visible in the image above). Removal of these two screws allows the entire autowinding mechanism to be levered away with little effort. Once removed, the mechanism can be disassembled on the bench, cleaned, and reassembled as a complete unit.
With the rotor out of the way I pulled the stem and turned the movement out of the case.
The dial was in fine shape considering it’s age and the hands appeared to still have the original luminous paint.
Removing the hands and dial exposed the calendar works which was heavily lubricated with thick watch oil. Puddles of oil appeared even on the calendar ring which is quite unusual as excess oil is about as detrimental to a watch movement as lack of oil.
Oil had pooled on the back of the dial as well and spots were even found inside the watch crystal. Clearly the previous watchmaker felt strongly about lubrication.
I dabbed the oil up with some watch paper and Rodico before settling in to disassemble the movement. Despite the excess oil, my impression of the movement was good.
The calendar works came away first as it was necessary to break down the dial side of the movement to gain access to the Cannon Pinion. The Cannon Pinion is friction fit (on the dial side) to the long post of the Center Wheel which passes through the bottom plate; if the Cannon Pinion is not removed, the Center Wheel will not come away from the plate.
Sadly, removal of the calendar components did not go off without a hitch. The Date Jumper, which is spring loaded and acts as a brake for the Calendar Wheel, took flight during disassembly, never to be seen again.
On the bright side, the movement was about ninety-nine percent free of rust. Even the keyless works were clean, although like the rest, heavily lubricated.
Flipping over to the topside, I commenced disassembly of the gear train. Again, excess oil was present throughout.
Utilizing both the old L&R cleaning matching and an ultrasonic bath, I cleansed the disassembled movement in strong watch cleaner. Reassembly is a slow and painstaking process, but in the end the watch movement is put back together with the proper type(s) and quantities of watch oil (and grease) to ensure its proper running for several years. I usually replace the mainspring during service as well but in this case the supplier delivered the wrong spring and I so decided to give the old one a go. The result was a strong and consistent beat- hooray!
Finding a replacement Date Jumper took a bit of time. The Tissot 746 is a calibre that hasn’t been in production for quite a while and it seems spare parts production has ended as well; however, the movement is identical to the ETA 2551 (Tissot probably just put their badge on an ETA supplied ebauche) and I was able to find the ETA Date Jumper on eBay. Within a few days I had the part in hand and ready for installation.
I reassembled the date mechanism and returned the dial to the movement before installing the watch hands. The sweep second hand has a slight bend to it but seeing as it’s irreplaceable, I decided to leave well enough alone and not chance straightening it.
The case received a full cleaning and new set of gaskets. The gaskets in the crown were replaced for good measure. A quick buff with a Scotchbrite returned the brushed finish to the case. With the aesthetic work done I installed the movement followed by the autowinding mechanism.
I gave the watch a full wind on the Cyclotest which spins the watch on three axes; this action winds the mainspring via the autowinding mechanism and also allows me to test the timekeeping ability in multiple positions (as if one were wearing the watch on his or her wrist). Ten hours on the Cyclotest equated to a bit more than forty hours of power from the mainspring which is pretty good in my estimation (I should note this is only the third autowinding watch I’ve worked on though).
Unfortunately there is a one little gremlin that still needs my attention. As you may have noticed, the hour and minute markers for this timepiece are not printed on the dial- they are actually part of the tension ring which holds the watch crystal in the case. When the original crystal was removed from the case for cleaning it developed a crack which I have yet to address. I removed the tension ring from the crystal and installed it in a new watch crystal which had substantially the same dimensions as the original but the fit isn’t perfect which means the case may not be absolutely watertight. Original crystals are no longer available so the solution will be to either leave it as it is, apply an adhesive to ensure a watertight fit, or repair and reinstall the original crystal. My desire is to repair the original, but it will be a tricky fix and honestly I’m not sure it’s possible. I’ll just have to see how it goes.