Flashing 2.0. after battery replace and memory clear

[masterbeat]

Hi, i just purchased two used Bally 5500.  After replacing battery and clearing ROM, both power up, one works fine, the other slowly flashes 2.0. (has two . . lit) and 20 flashing slowly in top left.   Looking at manual and error codes, it says that this means "optics on the coin optic decoder have been blocked for too long."   Hmm, ok, so I took out coin comparator, cleaned, and even replaced with the coin comparator from the other working machine.  On power up, still get the slow flashing 20.  So am I interpreting this error code incorrectly, or are the coin optics somewhere else?   When inserting a coin it goes straight through to the bin...


Any help would be greatly appreciated.

[Sunrise Side]

Below the comparitor is a coin optic. Could be coins jammed at that point and blocking the optic or the coin optic need disassembled and cleaned.The optic has a prism inside that needs cleaning also.