Hopefully this info can help someone. I had a Pandora’s box 5 arcade version in my Chewlix that would have intermittent problems with player one 5th button (pin 26). Sometimes it would act normal then suddenly act as if it was always on and grounded. Turned out to be a faulty surface mount 10 kohm resistor array (labeled 103) that was measuring low at 2.5 kohms. With a regular 10 kohm resistor, bridged the side closest to jamma edge and the other leg onto the surface mount capacitor labeled c11 and problem fixed.
