I very much appreciate the everyone's thoughtful suggestions. Tried different cables, exercised all the pots and switches, to no avail. Trying to insert pic of the electronics cavity, but not sure I have figured out how to do that properly.

. Gary thought that it might be the capacitor.
I see current note posted by Mica, so will try her e-mail directly.
Thanks again everyone for your help! Have wanted an Alembic for decades!
Russ