The radio and original receiver were bought used from a friend who had only used them a couple times. The problematic receiver is brand new. I've tried mounting the servo horn in different locations but I still get limited rotation in one direction. I'm going to try switching out the receivers to see what happens. Like I said, I've had the local pro guys at the track take a look at it, and everyone seems to be confused as to what is causing the problem. Thank you for the responses.