We’ve had one of these before, and quite some time ago… These are quite rare, and were used in the British nuclear submarine fleet. As you can’t have luminous compound there (it would set off all sorts of radiation alarms), they have no luminous compound, but a while dial with black markings and hands, so that the watch can be read nicely in the low light conditions in a submarine.
The start/stop/reset pusher on this one does nothing, but the movement itself runs well. The case back shows the usual nuclear submarine markings – the scratched out 3306 had a luminous compound dial, so these have that scratched over and punched “3312” on top of that. There are newer versions that how 3312 in the original number as well.
Luckily enough, I have a decent photo from the earlier 2220 I serviced, and I used that to produce a CAD drawing of the spring using FreeCad. This super software also produces the tool path, and if you want to make one of those yourself, you can download everything you need from watchparts.org.uk – I’ve uploaded the drawing etc. to there.
Looks perfect, and works perfectly as well.