The battlefield optos see the ball at the sides but not in the middle; the fault disappears with the playfield glass off.

The Shadow: battlefield misses balls in the centre

Cause: The transmitter beam is so wide that light bounces off the glass back into the receiver.

Checks

• Confirm the fault goes away with the glass removed.

Fix

• Slip a 3/8 inch length of black heat shrink tubing (unshrunk) over the transmitter, and over the receiver if needed, to narrow the beam.

Systems

• WPC DCS

Games

• The Shadow

Related tips

• Locking a ball serves two balls and fires a sling: faulty coin door interlock switch

Source: Repairing Williams/Bally WPC Pinball Games from 1990 to 1999, Part Three, Clay Harrell (pinrepair.com)