So you are only having problems while docked in the car? That is my problem too. Only mine is a Mk2a. In fact, it is the right channel that is giving me problems. I have to push on the right side of the Empeg to get the channel back, but it usually goes away after a few bumps in the road.

For me the problem appeared after the do-nothing stereo guys pulled the dash apart to fix a reception problem with the headunit (they didn't succeed).

Stu