I have a intermitten arch rotation problem on a laser 4000 at 90 180 270 degrees. Instead of turning 90 degrees it turns about 45 degrees when ever it fails. I have replace 15,16 and 17 sensors and cables. Same results It may go for 100 cars no problem. It could fail 3 times in a row another time . Swivel is now new same problem.I have watched in jo card sometimes all leds went out on the card that shows 15,16 and17outputs .seems that the cam was not covering any sensor?I put a piece of metal in front of each one and leds lit in jo.reset laser washed cars again 10 cars later at the 90 degree turn drivers front it again only turned 45 degrees kitty corner across car jo showed15&16 leds on never made it to 17 led system shut down always arch rotation error? In manual mode I can not get it to fail.One thing sometimes when I press arch button on joy stick it does not always stop right on the 90 Degree mark I have physically checked festoon really did not see much there?Any help would be very much appreciated!!!! THANKS, BONES