Joe,
I had wires inside my axle's originally - and they don't provide mounting points inside the axle to stop the wiring from flopping around.
After a number of years, I got a short in my second axle and couldn't figure out why - Until I put a post up here. Someone else had the same issue and suggested I break the circuit and figure out which axle and which wheel.
Turns out the wire inside had chafed itself down to bare wire and was shorting out.
I rewired with zipties and check it annually for wear to ensure it doesn't happen again.
Just my two cents
