Any repair experience with Fulltone TERC?

[Moff40]

Hi All;

Does anyone here (maybe MJMP?) have any experience repairing the Fulltone TERC (That Eighties Rack Chorus)?  They are a replica of the Songbird/Dynatronics DynoMyPiano/Tri Stereo Chorus, all analog.  There are basically two modes of operation, a "preset" mode (which is that slow chorus popularized by Michael Landau, Dann Huff, Steve Lukather, etc.), and a manual mode, where intensity of each of the three delay lines and the modulation speed can be altered.

Mine has started acting weird.  The preset mode works fine, but manual mode will only work OK for a few minutes, and then just stops sweeping, as though the modulation speed has been set to zero.  I have not been on the manual mode setting when it stops, but switching from preset mode to manual mode (via the front panel pushbutton switches).  Clearly the individual modulators are working, because the preset mode does what it should, but something is stopping the manual mode from "spinning up".

I opened it up and looked for swollen caps or visible connection issues.  There are three Vactrols inside, and given that the speed of the modulation in manual mode doesn't speed up or slow down immediately, but gradually, like a Leslie, I suspect one might be flaky.  the challenge is they are marked "Fulltone Opto1245", and no visible "normal" part numbers otherwise.  With Fulltone out of business, I have no way to find out what a replacement would be, or where to get it serviced.  No schematics online, no ideas of what to test and/or where.

[MarshallJMP]

Sorry no experience with these. If you find a schematic I could have a look but I never worked on these.