I love these little Radioshack Moogs! I have a MG-1 of my own that I overhauled and heavily modded a while ago, and I’m always happy to bring another into the shop. They are so simple and there are only a couple parts that are hard to find– the sliders, the switches, and the MM5823 frequency divider ICs. This MG-1 was not in too bad shape, and the foam under the panel had mostly been removed already, but had one of the three divider ICs not working.
If you have several octaves of a handful of notes not playing, the MM5823 frequency divider ICs are the culprit. I found a clever replacement solution from Flatkeys, a company in the UK— a little SMD board that fits right into the place where the original 14-pin DIP IC went.
There was also a slider with a broken wiper, but I couldn’t find any sliders of that type with the right value (10K) anywhere on the internet, so I bought a 2M one from Syntaur, took both apart and swapped out the resistive strips– as I was doing it, I was telling myself, “I am doing a ridiculous thing,” but it worked.
Work done: replaced all electrolytic capacitors, cleaned switches, cleaned and lubricated sliders, replaced MM5823 IC, replaced one bad slider, added 1/4″ output jack