At power-on the trunk on the left of the playfield opens and closes over and over, and balls are not loaded properly for multiball.

Pinball Magic trunk keeps opening and multiball won't load

Cause: The trunk optos are not reporting correctly, most often from cracked solder joints on the opto boards; loose LM339 chips on the backbox switch board can look the same.

Checks

• Watch the trunk optos in switch test while blocking each beam.
• If several optos misbehave together, check the switch matrix board LM339s as well.

Fix

• Resolder all the joints on the trunk opto emitter and receiver boards.
• Reflow the switch board LM339s if the fault persists.

Systems

• Capcom

Games

• Pinball Magic

Related tips

• Prove whether dead switches are on the playfield or the switch board
• Where the boards sit in a Capcom backbox
• How the Capcom switch matrix is wired
• Dead switches from failed SIP resistor networks
• Groups of switches dead or intermittent: loose surface-mount LM339s
• Pinball Magic trough serves two or three balls at once
• Pinball Magic can be converted to Williams flipper mechanisms
• Pinball Magic wand magnet fires at most three times in five minutes

Source: Capcom Pinball Problems/Solutions