on my laser 4000 the arch runs wide on the drivers side ,usually about 4 or 5 times a day.only the drivers side,(it runs wide on all soap and rinse passes but sets up ok after it goes to the home position but as soon as the arch goes around the back of the vechile it runs wide on the last pass) i have updated the vt board and replaced the x 30 prox switch and sensor.could it be the the ultrasonic or something else.....help!!