I've bought the bike new, so know her history very well ....
The gearbox has been renovated in 97 by a renowned French professional. so far so good.
A month ago, I broke the small spring pressing the changing arm... the gearbox was stuck in third.
As I thought I am clever enough, I opened it up to change the springs.
I bought a set of the 3 springs from BMW dealer and a reinforced spring for the arm from BMW Boxer Dienst Berlin.
I also bought a roller bearing to replace the locking nylon ring on the gear change assembly and of course a set of gaskets.
I opened up the gearbox, was totally unable to find the broken part of the spring, removed the changing gear assembly, put the new springs and the roller bearing, removed the input shaft to remove and change the input seal, then reassembled the gearbox again, calculated the needed spacers and closed the gearbox after changing the output seal and the change gear level seal.
Upon the first try, I noticed something that bothers me a lot :
All gears change are as smooth as they where, but the changing mechanism has a strange behavior : when I push the lever up to go in upper gears, it is fine. When I push it down, the gears shift down, but the lever does not come back up so I'm unable to get down one gear. I have to help the lever back in position in order to render the lever operative again.
Sometimes, the lever behaves as it should so I'm puzzled and seeking advice and remedies...
Of course, I would be pleased to hear there is a cure without disassembly....
Waiting to read from you Guys !
Thanks for your help.