This time I disassembled a 70-200 f2.8. better to say: I wanted to, because one of the two screws on the zoom barrel has been destroyed immediately after the first trial. The material is two soft, and the screw is glued from the factory.
In such cases You can do 2 things: to drill out the screw – difficult and after this You will have the threaded (steel) part stucked in the metal base (mainly aluminium alloy) – or You can try to make in it a groove for a bigger screwdriver.
Before this operation, You have to cover the lens and the housing – the small grinding machine produces metal particles – very dangerous for the lens.
It’s not very beautiful – but it works!