I recently bought a ESA 9210 powered Omega Speedsonic chronograph in a rather sad state. the Oscillator deck of this one is horribly discoloured and blackened in places, the battery strap screw is broken off on the main plate below the osc deck.
Just to see what was possible with this one, I removed the oscillator plate to see the main plate below. This had faired a little better, having gone a light rainbow colour and not heavily corroded thankfully.
I decided to check the oscillator plate, resonator, coils, index etc. The coils amazingly had continuity and of the correct resistances, resonator is clean, index is dull tarnished colour.
I gave the plate and the rest a clean--which didn't really clean it much, but built it back up with at least clean jewels and fresh 9010 for index and second..
It wouldnt run, even though the coils passed resistance checks, no oscillation, no hum very low current drain of 3uA.
Replaced the RC coil, It wouldn't run, still only 3uA.
Replaced the TR coil, now we had life, it runs, and taking 6uA, Strange, the original TR coil checks fine so does the transistor but just wont work.
I reinstalled the osc deck back to the watch, and jury-rigged a makeshift battery strap--my thinking is to assess the general operation (or not) of the rest of the movement, particularly the Chrono stages, prior to tearing into it for real. Ive read many a story of the chrono decks of these movements and would rather not have to pull that apart....
Well, The watch runs and keeps time, however on starting the chrono, will run for 5-10 seconds then stop, reset/flyback works as it should, the constant seconds display stays running when chrono stops, so looks like we got to tear into its devils-doings, the chronograph deck, with its weird vertical clutches and other oddities!....