I had the same problem recently and found out that the servo motor was siezed. I purchased a new one directly from Perfect Pass, but in the process of changing it out, I decided to try to free it up, so I cranked on the shaft of the servo with a crecent wrench and it broke free. I re-installed it and it worked fine. I would suggest logging into their website:
www.perfectpass.com and following their troubleshooting proceedure to determine whether you have the same problem.