Hello AtariAge!
I have recently picked up a CompuMate (from Venezuela, of course), serial # BC 0100028381. Right now there is a bit of an issue with mine. Every time I switch it on, either I am stuck with a blank black screen or a mess of different coloured bars, accompanied with a buzz. The coloured bars and hum are different colours and pitch every time. It might just need a good cleaning, but if anyone else has any other tips, I would appreciate it.
Thanks
Here are some photos of whats been happening