The blinders do not move.

Tommy: blinders do not move (servo motor)

Cause: Most often the cheap servo motor under the apron has stripped its plastic gears.

Checks

• Listen and look for the servo turning without moving the blinders.

Fix

• Replace the servo motor.
• Plug it in the right way: on the 3-pin .100" servo connector, the left pin (seen from the player's side, often marked red) is +5 V, the centre ground, the right the signal. Do not trust the colour marks on a replacement servo; a reversed plug can damage it.

Systems

• Data East/Sega CPU Version 3b

Games

• The Who's Tommy Pinball Wizard

Related tips

• Tommy: quick blinder test using expert mode
• Tommy: adjust the blinder open and closed positions
• Tommy: blinders dead with good voltages and wiring
• Tommy: CPU and display EPROM types and latest versions
• Guns N' Roses with a shaker motor was probably built for Japan

Source: Repairing DataEast 1987 (Laser War) to Sega 1995 (Batman Forever), Part Three, Clay Harrell (pinrepair.com)