I think IDWT hit it on the head. I’ve seen multiple magnet failures on two side by side units that are only 10 years old. You need to determine if it’s the DZ or slowdown magnet. If it fails that often, park the car on the magnets and jostle the tape around while watching the selector LED’s, or watch carefully and while parked on the magnet, see if it drops out for a second. And if nothing pans out there, check the COP selector wiring.