The flipper stays up after the button is released.

Flipper sticks in the up position

Cause: A worn rubber coating on the flipper pawl catching the end of the EOS switch (which may also be frayed), a flipper too tight in its playfield bushing, a broken or missing return spring, or welded cabinet switch contacts.

Checks

• Check the pawl coating and the end of the EOS blade.
• Check the bat has some vertical play (about 1/32 in).
• Check the return spring.
• Check whether the cabinet switch contacts have welded together.

Fix

• Recover the pawl with heat-shrink and repair or replace the EOS switch.
• Readjust the bushing gap with the flipper tool.
• Replace the spring.
• Separate and file the contacts, or replace the switch blades.

Systems

• Williams System 11
• Williams System 11A
• Williams System 11B
• Williams System 11C

Related tips

• One flipper does not work at all
• Weak flipper: dirty cabinet button
• Flipper dead on a System 11 game
• Flipper button sticks
• Flipper buzzes and vibrates when held
• Flipper sticks up and its sleeve cooks: EOS bent so it never opens
• Flipper coils have two windings
• How relay-enabled flippers work

Source: Repairing Williams System 11 Pinball 1986 to 1990, Part Two, Clay Harrell (pinrepair.com)