If holding the flipper up repeatedly scores, then it probably isn't a vibration/sensitive switch issue. I would be looking for a short somewhere between the flipper switches/coils and the orbit switch. I just glanced at the manual and it doesn't look like there is overlap between the flipper switches or EOS and that switch in the matrix, so my guess would be it's not a board issue, but rather two paths shorting together somewhere. But if no luck there, I would look at the ICs and transistors associated with the row/columns those switches are on. Good luck! Hopefully it's something simple...wires touching each other or a mech somewhere, etc.