About half the time a shot into the sanctum lock is flung up into the metal guide by the magnet and dribbles back out instead of locking. The lock switches and the wall work normally.

Sanctum lock magnet throws the ball out instead of locking: adjust the magnet core

Cause: The height of the magnet core under the lock is off, so the magnet pulls the ball at the wrong angle. Playfield pitch and level also affect it.

Checks

• Check the playfield pitch and side-to-side level.
• Look at how far the magnet core sits below the playfield surface.

Fix

• Raise or lower the magnet core a little at a time and test until balls lock reliably.

Systems

• WPC-Security (WPC-S)

Games

• The Shadow

Related tips

• Locking a ball serves two balls and fires a sling: faulty coin door interlock switch
• Lock drop target stays down in play but works in test: adjust its microswitch

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