One or both flippers do nothing.

Flippers dead: fuse and coil voltage

Cause: A blown flipper fuse, a broken power wire or a broken coil winding.

Checks

• Check the flipper fuse: F4 on the power supply board from Flash on; a fuse under the playfield on earlier games.
• Black meter lead on the side rail, red on each coil lug: expect 28-35 V DC (50-70 V on Firepower II and later). All three lugs should be live.
• Only one or two lugs live: the coil is broken. None: blown fuse or broken main power wire.
• If no lug is live but the fuse is good, check power supply connector 3J3 pins 4 and 5, which feed the flippers.

Fix

• Replace the fuse, coil or wire as found.

Systems

• Williams System 3
• Williams System 4
• Williams System 6 / 6A
• Williams System 7

Related tips

• Where flipper power comes from
• No solenoid voltage
• Score displays weak, dim or dead with fuses good
• Pull the coil and lamp fuses for the first power-up
• Display high voltage out of range
• Game resets when both flipper buttons are pressed
• Power at the flipper coil but no flip
• Flipper dead: burned coil

Source: Repairing Williams System 3 to System 7 Pinball 1977 to 1984, Part Three, Clay Harrell (pinrepair.com)