Remove the bottom plate. Put the MiniMoog on your work bench, standing up on one end cheek. Tape the synt together, so it doesn’t swing out while standing up – that would make it topple over. Connect power and audio out.
Under the key bed, there are three bus bars. Counting from the back, they are Gate OFF, Gate ON, and in the front: CV. If you have problems with double-triggering, or trig-on-release, there’s bad connection on the Gate bus bars. If you have problems like unstable pitch you have bad connection on the front (CV) bus bar. If the note changes drastically on key release, you have a problem with the timing of key contact springs hitting the bus bars. Mostly you need to bend the CV contact spring slightly, so it hits its bus bar before the gate is turned on (and leave it before the gate ir turned off).
Cleaning procedure, preparation
Rotate the three bus bars 1/4 turn using pliers.
Turn on the Mini so you can hear the keys.
You’re going to need isopropanol, 5-10 Q-tips, and one pipe cleaner. It has to be the type of soft pipe cleaner that are used for kids’ crafts, not the rough ones with metal wire ends sticking out.
For each key
Drench your tools in isopropanol. The better way to do this is to have a small jar (a bottle cap) and dip your tools in it. It’s going to sound glitchy while you’re working, but as it dries up, contact gets better.
- Using Q-tip with isopropanol: Clean the three bus bars at the location where the key springs make contact. There’s more space at the CV bar, so you can get the Q-tip in between the bar and the spring and rotate it. You have to be careful not to harm the spring.
- Using a Pipe Cleaner with isopropanol: Place it between the spring and the bar, work it both with key depressed and released.
- If you have cleaned it thoroughly and still have pitch glitches, check if you happened to bend the contact spring in step 1. If so, use a chopstick to push the base of the spring a pit closer to the CV (front) bus bar.
Sometimes the gold plating is worn off, and the contact spring can’t be saved. In that case you will have to get new ones. I’d say that’s unusual but not unheard of.