Apparently one can rotate the zoom ring and focus ring without mounting it on the camera.
I don't think you have to worry about the lost. Just read the
(1.) I have never use this lens.
(2.) Crack in the barrel and does not interfere with the operation.
OK, how did he know that it will not interfere with the operation
if he never use the lens? You have to use the lens to know it work.
Just my two cents