Quoted from frobozz:
Sure there are.
The reset relay has a switch between Black (the actual source voltage from the transformer) and BLU-Y-W. Then the game over relay has a switch between BLU-Y-W and Red, and Red goes to the flippers among other things. See sections 12E and 13E on the schematic, along the very top.
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).