Problem is going to be with the lower flipper as it flips the upper flipper. Could be a broken coil wire or a bad EOS switch. Post a few photos that clearly show the EOS and coil wiring. If the switches are original this might be a good time to do a flipper rebuild.

Definitely rebuild that mess. Also note the amount the flipper shaft extends through the crank is too much. Either wrong flipper or improper setting. Flipper shaft should extend through just a small amount and there should be nominal vertical play.