Brakes grabbing

MFL wrote:
Hey JR, this is a common issue, but normally takes at least a light touch of pedal, that can result with braking similar to pulling the pin. Very aggressive, tires chirp/maybe smoke. As Grit mentioned, turning the gain way down will help, but braking will be diminished.

It starts mostly intermittent, due to the wiring moving/bouncing inside the tube.

Quick fix..cut the wires going through tube, and run new cross wire outside the tube.

Sorry, I do not have enough info to tell the OP what the problem is. But what I can say is unless a cut and run more wires "tech" has really screwed up already the problem is NOT a short in the axle. Unless something is wrong elsewhere, the only time current flows in/out of axle is when break-way or controller signals apply the brakes. Now there can be a short 2 ways; brake wire to axle. The magnet does not get power/shoes don't move to drum/brake does not work. Or brake wire to ground wire. The magnet does not get power/shoes don't move to drum/brake does not work.
The 3rd, and most common issue is a broken wire (brake or ground) in that case the magnet does not get power/shoes don't move to drum/brake does not work.
As the OP is not saying the brakes are failing to apply, the issue is not wires in axle

If I was tasked with fixing I would first ask if any trailer lights on. I suspect that the issue is the brake wire is getting power from someplace it should not, most likely in the plug.