Hi Retrotoyguy. Can you post a picture of what you have at the pop mechanism that brings the ball back up to the playfield from the mystery hole subway? The manual says that switch 55 is an opto but you can't always trust them. wouldn't be a fun job to change an opto for a switch I imagine. Does the switch look like a hack or a factory install?

Optos here but won't come with the wire and plug to connect to the loom.
]http://www.rtbb.com.au/catalog/product_info.php?products_id=1311&osCsid=3b3221edc890e1b70302aca5931d0a90] Transmitter
http://www.rtbb.com.au/catalog/product_info.php?products_id=1312 Receiver