Have you tried simply turning the key switch off and then on againIJ Does this work temporarily, or not at allIJ I believe A1 means "momentary header height circuit failure", so it might be a bad connection. Good luck
If you still have the old style hard plastic square raise_lower button, it is probably causing the problem. I think all of them have failed by now around here. A1 fault means a failure in the raise_lower circuit.
what is the software in your header controller. we have had alot of problems with the earlier softwares keep coming up a1 and then not work. we sent them in to get reprogrammed on the 21 series but now i think you have to by a new controller to get the latest and greatest which is kind of an expensive fix but you may have to do that. but put the newer 4 way switch in first. the new software is supposwed to hold memory better and has worked well for us. good luck