Greetings! It's been awhile since I've posted, and I thought I "otter foller up" on my E-Pro repairs.
I did get my theremin back from Moog, after three full months. During the third month I pestered them a lot, until they must have gotten tired of me and decided to do the job! It's funny how you have to fight nowadays to get anything done, be it theremin repair or prescription renewal, etc.
Basically, they found a bad mini-circuit board in the pitch antenna. An inducer was burned out, at least. A replacement board was located and installed. Then another technician did some deeper testing and calibration, letting the instrument run for quite a while, off and on. The problem with the two large cement resistors in the control board running too hot didn't recur.
My E-Pro is doing great now. If your E-Pro ever experiences the symptoms which mine did, you may have a problem with the little circuit board in the pitch antenna. Reading back over my posts in this thread could be helpful.
I wish you a great new year!