Zipper flippers have play or don't close cleanly.

Sloppy zipper flippers: worn base plate slots and bushings

Cause: The bushings in the moving base plate slots, and the slots themselves, wear; the V arms and their pivots wear too.

Checks

• Remove the unit and check slot and bushing wear and pivot play.

Fix

• Fit slightly oversize bushings: the Williams WPC flipper link spacing bushing 02-4676 takes up much of the slack.
• Smooth low spots in the slots with a rotary tool.
• Trim the nylon playfield bushings if the slot bushing washers rub on the base plates.

Systems

• Electro-mechanical

Games

• 4 Queens
• Bazaar
• Capersville
• Cosmos
• Dixieland
• Dogies
• Doozie
• Four Million B.C.
• Hayburners II
• Joker
• Joust
• MiniZag
• Nip-It
• Op-Pop-Pop
• Rocket III
• RockMakers
• Student Prince
• Surfers
• The Wiggler

Related tips

• Flipper rebuild part numbers for System 11
• Coil sleeves and flipper rebuild spares
• Flipper link spacer bushing wear limits
• Flipper rebuild step 6: pawl, plunger, link and bushing
• WPC-style conversion: plunger, springs, bats and coil
• Rewinding a plastic-encased zipper flipper close coil
• Which games have zipper flippers
• Bally zipper flipper solenoids changed at Capersville

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