Riding home from work tonight and about a km from home, couldn't change down into second or first.  Kept going and on stopping can now only select fourth or fifth.  The gearlever doesn't seen to return to a mid position, just drops down.  What's up...any ideas??
2002 620ie, I've put about 80k on her, runs daily 150km...no indications of impending doom at all.   

John

worn out clutch/friction plate(s)?

Return spring, internal linkage?  With 50,000 miles it could be anything and it sounds like its going to require opening it up.

I don't think it's worn plates I would think something in the linkage, best get it checked soon.

First look at the lever.  It may be hitting something.  Unlikely, but easy.  Then look under the left side cover there is a gear shift selector.  The adjustment may have slipped or the spring may be broken.  After that the scenerio gets bad.