Quoted from asay:It's really common for a foggy upper playfield to be blocking that ace in the hole opto. If they were firing when you had it apart it's likely this is the problem.
How would this happen? The optos (inside and out) are horizontal and fully above the mini-pf--they do not transmit thru the plastic pf. The mini-playfield (foggy or not) can't affect the optos here.
Dumb thought, but--could the instant AitH start result from extra-easy settings? (Not sure--never tried this as mine is always on standard or hard.) Have the guy check the installed difficulty level?