After fitting a replacement lamp driver board set up for LEDs, LED bulbs light in the always-on GI sockets but never in the controlled (flashing) lamp sockets. Incandescent bulbs work there.

LED bulbs work in GI but stay dark in controlled lamps: wrong type of LED

Cause: The bargain LED bulbs used were wired for the opposite polarity to these sockets, so they could not light on the controlled lamp circuit.

Checks

• Confirm the lamp board's LED jumper is connected to a switched lamp common in the backbox.
• Try one LED from a pinball LED supplier in a dead socket.

Fix

• Use LED bulbs made for pinball (non-polarised or the correct polarity for the game).
• Fix any weak lamp grounds found along the way.

Games

• Six Million Dollar Man

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