Thanks Paul. Yes I have a KG107 with heading bug and two KX155 for CDI. The top KX155 is an ILS and the bottom is a VOR/LOC. The CDI on the bottom (VOR/LOC) is the one to use in GPS mode.
I can be flying in heading mode while setting the GPS in the KLN94. Then press NAV and adjust the KX155 CDI to the new desired track. Then within 5 seconds I adjust the heading bug on the KG107 to match the CDI. The plane will steer to the new CDI/Heading and go past it about 10-15 degrees. Then it will slowly, very slowly attempt to fly back to the CDI/Heading about 1 degree every 4-5 seconds.
Last night I set up a GPS approach, got ATC cleared to the first point. I had the GPS approach loaded, pressed NAV, moved the CDI to the desired track and set the heading bug on the CDI course. The plane turned toward the new heading and blew past the first GPS approach point.
My IFR instructor has many hours with the KAP100 and KLN and thinks there is something wrong with the unit.
I think it must be something between the KX155, the KAP100 and the KLN94 not reading the DTK.
I am going to label it in-op I think.
Thanks!