Originally posted by Hornet
Somehow I managed to get the built on lens hood of the F300 stuck in the extended position. Probably it is cross-threaded. I've tried putting as much force into turning it with my hands as I can and have even tried using 2 belt wrenches to increase the leverage but nothing - doesn't even give the slightest indication of movement.
It might not be cross-threaded: I remember that my F* 300 hood became stuck in the extended position; I had bought the lens new and it was probably less than a year old at that point. I resigned myself to just leaving it that way, as I wasn't about to try to force it... but eventually it came loose on its own. My guess is that it was likely a temperature change that allowed it to come free; but whether it was the lens warming up or cooling down I couldn't say.
So, before you try anything drastic, just keep working at it and maybe you'll get lucky like I did (I believe it was several weeks before my hood finally loosened up).
I eventually learned to NEVER tighten the lens hood in either extended or retracted position, because the design is so prone to locking up if you do. Always make sure that the hood can turn freely at either position, and you'll never have the problem again.