The left flipper is weak on the upswing and slow to return; the coil overheats and its sleeve can stick inside it.

Weak flipper slow to drop back, coil cooked: worn EOS switch

Cause: The end-of-stroke switch on this game carries the coil's power-winding current. A pitted, corroded EOS that did not close well made the flipper weak, and one that did not open let the power winding stay on and cook the coil.

Checks

• Clip a jumper across the EOS contacts (game off, then test): if the flipper is strong with the jumper, the switch is the problem.
• Inspect the EOS contacts for pitting and check it opens at full stroke and closes firmly at rest.

Fix

• Replace the EOS switch rather than filing it, and replace a cooked coil and sleeve. A full flipper rebuild is worth doing at the same time.

Systems

• Williams System 9

Games

• Comet

Related tips

• Flipper weak: worn plunger, coil stop or sleeve
• Williams 50 V fat flipper coils ranked by strength

Source: Pinball Repair help group!! (Facebook group)