If you find one let me know. The best shop I have been able to find is Muncie in Indiana. Their web site is
http://www.muncieaviation.com/. I spent a lot of money on a number of shops who really didn't know what they were doing. I can't remember the name of the fellow I worked with a few years ago but I believe he may have retired anyway. To get the unit fixed I had a local shop remove the unit and send it to Muncie. It was worth the hassle. After fooling around with a number a shops in the past I wouldn't bother with anyone other than Muncie if the problem requires tearing into the unit.