The sensors on 75s are the newer style hall sensors, so ar difficult to check with a multimeter, unlike others.
The difference in the reading could be as simple as which way you connected your multimeter. One way would conduct, the other not.
I doubt it's your intermittent problem. If the were open circuit, you would get a light all the time. I'd check you're wires for wear, and an intermittent short. Favourites are the front wheels.
A testbook /T4 (Testbook version 4.Computer Diagnostic System) session would tell you where the problem lies.