Well....add me the list of people with a sensor board failure. Put in a new 25.5 into my f1. On my second day of practice motor started to feel like cogging. I put another motor in and it was fine so I knew it wasn't the sensor wire or esc. I then put the motor on my motor analyzer and it wouldn't spin. Put another motor on the analyzer just to check and that motor spun fine. I then took the motor apart to see if there was any rubbing on the sensors and there doesn't appear to be any. Sigh.