Jan,
As suggested I adjusted the 0 center of the yoke, but no joy.
Then I did uninstall ixeg B737 after downloading a fresh copy from x-aviation, and installed the freshly downloaded file. Unfortunately still not able engaging autopilot. Funny thing is FF767/757, zibo.s and other have no problems. Until recently the Ixeg b737 ran flawless. The only thing I added since were a few different liveries. Yes my yoke/rudders (CH) are still gameport (using gameport/usb adapter). I am familiar with flying different types of rw boeings, although I never flown the 737 (except in lvl.D sim).
Beside the autopilot problem the Ixeg 733 flies fine.
Also I recently upgraded xplane11.26 to xplane11.40, so the majority of non issue flights were on version .26.
Or time to acquire an Alpha Yoke from honeycomb.
Any suggestions?