I used to own a R52 with my neighbor. I came back from the elevator one day and he had everything tore apart, voltage meter in hand, checking this and that...could not get it to unload. I hopped up into the cab and was kind of fiddling with different things, and for whatever reason, I decided to hit the air valve on the air ride seat and let some pressure off. BINGO! auger started right up and worked fine. Evidently, so much air pressure in the seat that the proximity switch would not work. Neighbor was sort of emberassed...didn't know wether to cuss or laugh. He'd been messing with it for quite some time before I showed up. He was a pretty big guy, so probably had the seat maxxed out. Maybe not your problem, but it made me recall this incident.