I agree if it is not clipping a lock, you have a magnet in the wrong position, or cheak to see if your top final is hitting before DZ . Can you run this car to the top from car top? put someone inside the car, and have them give a call as your on top. Look at everything when you stop. There is also a diode in the controller relay board D 22 if this is bad as the car hits dz it will switch to insp, and then back to normal, causing the car to get a selector fault. Just a idea hope it helps.......Good Luck