The left flippers don't work, and the meter shows odd low AC readings instead of about 50 V DC on the flipper power lines when measured against the cabinet or MPU ground.

Flippers dead and voltage reads nonsense: measure to the flipper board ground

Cause: The flipper supply returns to its own ground on the flipper power board, so readings against cabinet ground are meaningless. Once measured properly, the lower left flipper coil had a broken winding and a loose solder joint on its power lug.

Checks

• Measure the flipper power pins (15J3-1 and 15J3-2) against the ground pin on the flipper power board's 15J2 connector.
• Follow the voltage down to each flipper coil using that same ground.
• Check the coil windings and lug solder joints on the dead flipper.

Fix

• Resolder the loose joint and replace the coil with the broken winding.

Systems

• Bally 6803

Games

• Truck Stop

Related tips

• Upper flipper weak or dead when the lower one is
• One flipper sometimes locks on: cabinet switch contacts pitted and sticking

Source: Pinball Repair help group!! (Facebook group)