I have a recurring issue with my STEC55X autopilot. The airplane remains right of course about 2 degrees (1/4 scale). It’s especially noticeable during coupled approaches using either the GPS (GNS430W) or Localizer. I have done inflight A/P calibrations on the PFD and manual alignments with a technician using a special screwdriver without success. It’s most noticeable during an ILS approach. The AP tries to center but then drifts right of course. I have replaced the PFD, based on apparently low voltages noted by my avionics shop, but the the problem persists.
If anyone has had a similar issue with the STEC55X please let me know if you resolved the problem. Attached is a picture of my PFD while enroute. Notice the airplane to the right of course on the CDI. Thank you for your help.