A flipper does nothing when its button is pressed.

One flipper does not work at all

Cause: A blown flipper fuse, dirty cabinet or EOS switch contacts, no 50 V at the coil (fuse, broken wire, bad bridge), or a bad coil.

Checks

• Check that flipper's fuse (each flipper has its own).
• File the cabinet switch and EOS contacts clean; the EOS should open with about a 1/8 in gap at full stroke.
• With the game on, measure DC from the side rail to each coil lug: 50 to 80 V.
• No voltage: on Fire! and earlier check the flipper power supply board (far right of the backbox); from Big Guns check the auxiliary power driver board. Voltage going in but not out means its bridge rectifier is bad.
• Ground the coil's middle lug (FL11630, F-14 Tomcat and later) to the side rail briefly with the game in attract mode: the flipper should pull in.

Fix

• Replace the fuse, switch or bridge found, or the coil if it fails the resistance check.

Flipper coils run on about 50 to 80 V DC.

Systems

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

Related tips

• Flipper dead on a System 11 game
• Flippers and lock kickout dead with good fuses
• Flipper power supply board (Fire! and earlier)
• One or both flippers weak
• Burning smell, then flippers, pops and eject all dead: broken flipper EOS switch
• LED flashers blink when the flipper buttons are pressed
• Interconnect board and flipper power board fuses
• A-bank coil not working

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