On an otherwise clean, adjusted flipper, the bat stays up or returns slowly after release.

Flipper stays up after the button is released

Cause: A magnetized coil stop holding the plunger. Over-winding the return spring to compensate only weakens the flipper.

Checks

• Check the return spring isn't wound extra tight.

Fix

• Replace the coil stop. On Gottlieb, the two coil stops from the rarely used backbox replay unit can be swapped onto the flippers.

Systems

• Electro-mechanical

Related tips

• Flipper EOS switch: gap, checking and cleaning
• Flipper buzzes loudly while the button is held
• Flipper drag marks on the playfield
• Weak flipper from an over-tight return spring
• Shock from Gottlieb metal flipper buttons
• Sloppy Gottlieb flipper: loose pawl collar or pin
• Sloppy Gottlieb flipper: worn shaft and shoe joint
• Rebuilding an EM flipper

Source: Repairing Electro-Mechanical (EM) Coin Operated Games to 1978, Part Two, Clay Harrell (pinrepair.com)