A pop bumper pulls down and stays down (with the relay, reel and bell locked on).

Pop bumper stays on after the ball hits it

Cause: The bumper's end-of-stroke (scoring) switch is broken, missing or misadjusted. On Gottlieb it opens as the bumper fully pulls in, cutting power to the pop relay. A spoon switch held closed by a misaligned skirt does the same.

Checks

• Check the EOS switch on the bumper mechanism opens at full stroke.
• Check the skirt stem is centred in the spoon switch.

Fix

• Repair or adjust the EOS switch.
• Re-centre the spoon switch.

Systems

• Electro-mechanical

Related tips

• Gottlieb pop bumper relay and score reel stuck on
• Game resets but no playfield solenoid works
• Pop bumper armature links: which to use and how they go together
• Making pop bumpers kick harder
• Cleaning and adjusting the pop bumper spoon switch
• Strengthening pop bumpers by removing coil windings
• Renew sleeves on flipper, pop bumper and sling coils
• Ball release hold coil won't release, big spark on its switches

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