I am pulling my hair out - There is a subway under the No Fear playfield that had 4 sets of optos. In the test menu, the "Popper 2" opto set is showing as X'ed (i.e. something is either blocking the path of the IR, or the sender and receiver are out of alignment. I have swapped 3 of the sets of optos around, hoping that the problem could be isolated to that pair of optos. It is not. It appears that all 4 sets of optos are fine - but the pin still thinks that the set in "Popper 2" is bad.
I have traced all wires from the pair of optos (send/receive) in question to the under-playfield opto processing board, and they are fine. I have also reflowed the header solder pins on the opto processing board.
But still the CPU sees the opto pair as non-operational. Any ideas?