The microswitch closest to the opto is not working. in test mode it doesn't show a ball there. I pull out a new microswitch with roller, put the DMM on the new switch, works fine, I put the DMM on the old switch to confirm and it works fine? on the DMM continuity, but still doesn't register on switch test. the opto switches read fine the switches behind it read fine, but what would cause the switch to give continuity on the multimeter, but not read in the system?