(Disclaimer: If you’re unsure, don’t do it. I took a small chance with this repair and would have accepted full responsibility if I botched it. It may be a fine line, but I’m posting this to help people diagnose, not repair.)

Anyway, here is what I did:

I removed the top cover by removing the five screws that secure it — two on each side and one on the back. Because the cover is attached by wires to the body, you cannot remove it and place it somewhere out of the way. I carefully placed the cover behind the organ so that I could stand it on its back.

There are separate circuit boards for each note, (each is labeled, fortunately) plus two others at the low end of the keyboard. Each circuit board is held in place with a long piece of wood extending the length of the organ, with foam on its underside. I removed the six screws that secure this piece and removed it.

I carefully removed the G circuit board by slowly rocking it back and forth while pulling upward at the same time.

After a visual inspection revealed nothing obvious, I started to gently wiggle each component with a non-conducting probe (I used the handle of a plastic inspection mirror).

Fortunately, one of the first components I wiggled — a capacitor — felt loose. The solder looked sound at a glance, but the lead was not connected to it. (You can see the lead poking through the hole in the solder at the top center of the board)

I re-soldered the connection, plugged in and played, and the organ sounded great.

It should be clear from this post that I don’t know much about Ace Tone organs, so I welcome comments. At the very least, I hope this info helps somebody.