Part of the problem could be dirty/worn/noisy volume controls or wiring/connections. There are two volume controls (one on the door, and a cheap unsealed one in the Vidiot sound section). Just had issues on my Baby Pac, fixed with some tech spray and moving the Vidiot volume potentiometer up and down to clean it. Previously had to fix some battery corrosion, so check any headers/wires/connectors, especially areas below the original battery location. Also the sound section has it's own test button, which can help to find the problem area.