If a failure as described in I.16. has occured, the consequence often is a blocked thread, that doesn't allow to unscrew the drive. In the worst case, the pressed in black tube starts spinning - nothing can be dismounted nor unscrewed...

In this case, the only remedies are the followings:

- first make sure, that you're trying to unscrew the right way round. mountain-drive has a left hand thread, speed- and high-speed-drive have a right hand thread. If the drive is mounted on the left side, the threads are vice-versa.

- second try to losen the grooved nut with a powerful hammer stroke on the extension of the box wrench. This often helps due to inertia.

- last and most serious action: you have to dismount the whole drive by unscrewing not only the left crankarm but also the self locking nut on the axle. Now (except speed-drives with plastic cover) you can pull off the whole unit to the right side. Please do it carefully to avoid, that a lot of balls and springs fall to basement!! Now you have to prepare a piece of aluminum or wood with a diameter of about 32mm. Turn or grind it to a conical shape on one end and hammer it into the black tube. Now you are able to hold the tube as well as to loosening the nut in the correct direction.

If you try to disassemble an older speed-drive (with plastic cover on the left side of the gear housing) this way, you have to snap-off the cover at the same time you are trying to pull the gear out of the housing.