Six of the eight lamps in one lamp matrix column never light, and the two that do work also glow faintly when another lamp in that column should be on. The bulbs work in other sockets.

Most lamps in one matrix column dead, the rest ghost: broken column wire

Cause: The column wire that daisy-chains from socket to socket was broken: one section was pinched and cut through, and a wire on another socket was hanging on by a thread.

Checks

• With power off, check continuity on the column wire colour between the lamp sockets; the real wiring order under the playfield usually differs from the lamp matrix chart.
• Follow the wire from the last working socket to find where continuity stops.

Fix

• Cut out the damaged section, splice and solder it, and resolder any loose socket wires.

Systems

• Stern S.A.M.

Games

• Family Guy

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