There are two solenoids that buzz. The alternating relay (L) and the ball release relay. The former buzzes whenever bumpers 2 and 4 are lit. The latter when a game has been started but no points are scored. They’re on when they’re supposed to be on, and I don’t see any way to get them to be quieter without major change.

There are a few solenoids that are supposed to be on. One of them is very noisy. We should find it and make sure it’s properly aligned to minimize the buzzing.