Ok, are familiar with voltage meters?
Next thing you will need ot do is check the wire on the starter housing, and, there will be a small wire coming off that going into the wiring harness, I believe brown. Then, up on the starter solenoid will be the other battery cable, and again, a feed wire coming off that, it should be blue in color and then goes into the harness as well. test voltages at those two points on the starter... Then , up at the light switch, you will find those two wires again, one on a terminal marked bat a and the other on a terminal marked bat b. I have a suspicion these two wires may be melted together in the harnes, in turn sending only 24v up to the switch. Let me know what you find..
Can you verify for me this connection at the batteries?
Also, if you have the capability, check your generator and voltage regulator to see if either one is shorting out internally
(do not replace either until confirming their conditions) If you don't have the capability, you will need to bring those components to a facility that does
THAT IS HOW OUR BATTERY ARE HOOKED UP WE HAD THE GENERATOR AND REGULATOR CHECKED OUT EARLIER FORGOT TO TELL YOU THAT WE HAVE NOT HAD THE STARTER CHECKED OUT BECAUSE IT STARTS GOOD
ANY THING ELSE YOU CAN THINK OF