Now and then the lock bar will not release the balls, and the game reports a check-switch message for switch 74 (Top Lock).

Ball lock bar holds balls and Check Switch 74 shows: top lock switch not being hit

Cause: The game audits switches and flags any that have not closed in about 30 three-ball games. The top lock switch is reached only by a tight shot, so it can simply go unhit; less often the switch blade, a solder joint or its diode has failed.

Checks

• In switch edge test, close switch 74 by hand and see if it registers.
• If it does not, check the switch gap, the wires and the diode on the switch, and the matrix row and column it shares.

Fix

• If the switch works in test, fill the lock with three balls by hand to close the switch, play the game out, then power cycle; the message clears.
• Fresh flipper coil stops help players make the shot that reaches this switch.

Systems

• WPC Fliptronics

Games

• The Getaway: High Speed II

Related tips

• "Check Switch ##" message
• "Ground Short Row" message
• "Row Short" message
• "Check Switch #" message at start-up
• Clearing a switch flagged in the power-on test report
• A switch does not register in the switch test
• "Switch is stuck On" message
• Row or column "ground short" errors

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