I used the search function and looked at the last 17 pages. Maybe someone here can save me some time.

My KFC200 AP is coupled to a G600. I sent the roll servo to APCentral about a year ago to have it overhauled ($5AMU). When I got it back, they had replaced all the electronics and the motor. It has worked fine, till now. It no longer tracks and does not follow the heading bug to the right. Anybody care to suggest someone for a checkout?

Unless somebody has a better idea, it will probably go back to AP Central after I troubleshoot it, if I can find the procedure around here. I seem to recall the servo is supposed to have voltage on two pins, but which two?

Does the flight direct give correct cues?

Call Jake at Bevan Aviation in Wichita.

Bite the bullet and replace it with a GFC500. You already have the G600, it should be a good fit. I know, it's easy to spend someone else's money. Otoh, the kfc200 has a knack to spend your money in $3000 chunks, doesn't take long until a new AP pays for itself.

If you do not see a new Garmin autopilot in your near future, this ^^^ is the starting point. What does the FD do when you move the heading bug? If it does not respond properly, the fault is not in the servo. Looking at it a bit differently, enable the FD and HDG and use altitude preselect and nose up/down like normal, but leave the AP turned off. If you can hand fly following the FD and the plane tracks the course, the problem is with the servo(s). Otherwise, the problem is elsewhere.

I too have a KFC200 connected to a G600 through a GAD43e. I pulled everything early in the restoration process and sent it to AutoPilots Central. It works great.