If you have a bad diode it will be at one of the corners of a rectangle that passes through the switches in question.
https://homepinballrepair.com/pinball-switch-lamp-matrix-troubleshooting/#switch-matrix-shorted-diode
Looking at row 1, positions 5-8 & 12-14 have no switch. An imaginary rectangle that passed through those would include switches 37-40 & 44-46. Of those I would suspect the Prison standups at 44 & 45, they take a beating.
If neither of those are the problem I'd check the rest and if you still don't find the issue I'd get out the logic probe.
As a sanity check have you pulled the connectors at J1 & J6 and followed the column/row test procedure to rule out a board problem?
Avondale, AZ
