Four consecutive lamps on the clock assembly never light in any lamp test, though the wiring, diodes and solder joints all check out.

A group of clock lamps never light with good wiring: reseat the bulbs in their sockets

Cause: The bulb leads were not making contact in the plastic twist sockets on the lamp board.

Checks

• Pull each dead bulb and look at how its leads sit against the socket contacts.
• Test the bulb by itself with a small power supply.

Fix

• Reseat the bulbs (turning them 180 degrees here), and bend the leads or pinch the socket contacts so they grip firmly.

Systems

• Data East CPU Version 3

Games

• Adventures of Rocky and Bullwinkle and Friends

Related tips

• Several lamps in one matrix row won't light: rusty sockets, diodes and joints
• One controlled lamp never lights, bulb is good
• Test a lamp socket diode in place
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• Lamps on a plug-in lamp board do not light
• Every CPU-controlled lamp is out
• One string of GI lamps very dim: replace the bad GI wiring

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