pixelpix wrote:
if this is the way Canon made the lens, then they have grossly under-engineered the mechanism for it\'s task.
What I am suggesting is that if the locking bolt is knocked when loose and the shaft bent, when it is tightened later it could cock over and jam in the thread. It may go in and out a few times gouging the thread wider and wider before that eventually happens. Normally when the bolt is tightened down it is under tension between the thread and the surface it locks against inside the lens and is therefore rigid. (It does require some force to start unscrewing a metal bolt in a metal thread because it has cold welded onto the thread .)
Or if the screw is once overtightened the bolt may deform in order to be shorter and fit, the raised part will gouge the thread as the bolt turns and eventually the thread will be so loose the bolt will cock over and jam.
It is the nature of mechanical things that they can fail some time after the damage was sustained.
