It seems to be a regular thing on Bavarias that the lower bearing of the rudder post stiffens (corrosion?). Anyway we have fixed our 2002 Bav 36 by getting into the rear compartment removing the rubber tube off the top of the lower bearing and pouring in some olive oil. Any oil may possibly work but that was all we had a hand. Then replace the rubber tube.
After a little use it loosens up.
Serendipity