i had the same problem last month
i thought the home flag 30mm was going off and tricking the machine
so i changed that and the festune wire
still did it
so i changed the front eye still did it randomly
so i put the amp on the rear eye and it guess what starting turning early on the back
try the x40 amp in the j3
for a quick check just swap the two out and see if it follows to the rear eyes
good luck
Mine did that awhile back but was on the front
my impact switch would shut it down
and i noticed the left limit eye was on, it was really cold that day so i wiggled it and then actually hit the back part of the plug with my wrench and it went off..........so anyways bad eye
next time it happens see if your right sensor is on in gantry or in jo
good luck
Check your x30 prox, if it's damaged, replace it, replace the x30 prox cable, also check for a bad connection and corrosion in the junction box. If you still have an issue, you may have a bad wire in your festoon cable. Good luck..