In article ,
writes:

It could
be due to a maladjustment in the CDI or in the Autocontrol IIIB. You can
probably determine which by seeing if the same thing happens when tracking
on a VOR radial and/or when coupled to a second CDI (if you have one).
Actually, from your post I infer that you have verified CDI accuracy against
aircraft position as shown on a moving map display. That would point to the
A/P as the culprit. But then you say that if you "set the heading but to
the right a little" you fly "right down the line". Do you mean that you are
slightly adjusting the DG's heading bug? This really shouldn't make a
difference, because to the autopilot this should just appear as a slight
change in the crosswind component.

I've pretty well determined that it is the autopilot. That is, the everything
acts the same in GPS or VOR and from either CDI. I was hoping that there was a
simple adj in the autopilot for "offset".

Chuck