After new flipper parts, the left flipper worked for a game, then stuck up; the new sleeve had heated and gripped the plunger, and the lights dimmed when that button was pressed.

Flipper sticks up and its sleeve cooks: EOS bent so it never opens

Cause: The EOS switch had been bent during alignment so it never opened, leaving the high-power winding on. These flippers have no transistor; the EOS controls the power.

Checks

• Hold the flipper fully up and check the EOS opens.
• Check for a warped sleeve or a coil that has started to melt.

Fix

• Replace the warped sleeve (and the coil if it's damaged), then re-form and gap the EOS.

Systems

• Williams System 11

Games

• High Speed

Related tips

• One flipper does not work at all
• Flipper sticks in the up position
• Flipper dead on a System 11 game
• Replacing the flipper plunger and link
• Weak flipper: dirty cabinet button
• Flipper rebuild part numbers for System 11
• After a flipper coil swap a 50 V fuse blows and the buttons fire flashers
• Every System 11 flipper has an EOS switch and coil diodes

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