The game boots and plays, but the ball lock mechanisms and drop targets never fire.

Ball locks and drop targets do nothing: blown fuses under the playfield

Cause: Blown fuses in the fuse block under the playfield near the left flipper, which feed those coils. They are easy to miss because they are not in the backbox or cabinet.

Checks

• Lift the playfield and find the fuse block near the left flipper.
• Test each fuse with a meter rather than by eye, and check the ratings against the manual's fuse list, since the printing on old fuse caps is often worn off.

Fix

• Replace the blown fuses with the ratings listed in the manual.

Systems

• Gottlieb System 80B

Games

• Hollywood Heat

Related tips

• Under-playfield fuses on System 80 games
• Drop target bank won't reset though it fires when grounded: reseat driver board plugs
• Test fuses out of the holder and never over-fuse

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