This MPC3000 showed some signs of use and abuse over these years, in fact allmost all screws had come loose, probably due to some heavy pad-banging!
That left the PCB’s floating around inside the housing, even the rotary encoder had come loose and had fallen inside. The soft key switch 1 also did not respond anymore to button presses, same for pad No9 which also did not always react when hit.
I replaced all the missing screws, thightened them all, exchanged the broken button, took apart the pad and cleaned the contacts.
Obsoletetechnology 