Quoted from EMsInKC:OK, but once solenoid power is on, then those switches would cause everything they power to be weak, correct? There are no other switches in the circuit after that except the button switches and the EOS. Obviously there has to be a switch to kill coil power at game over, but he is not saying that the other coils involved in the game seem weak, just the flippers. And in this case, it's just one flipper which seems to me, anyway, to indicate that it's not a matter of power getting to the flipper button switches and then on to the coils themselves, but rather a problem with that one flipper in particular.
In actual practice, the vast majority of the time, weak flippers are the result of dirty button switches, EOS opening too soon, or something wrong in the rebuild of the flipper (dragging, return spring etc).
OK, good point, I was responding to the forest without seeing the trees. There are, in fact, relay switches involved in the flippers... but they are incredibly unlikely to be the culprit, even less so in this case where it isn't both flippers that are weak. (The other things made weak by those switches being bad might not be as obvious.)