Thanks Paul, I will keep bookmark that website as to be honest, I have little faith in my 100-400 remaining in good condition once it returns.
Snoop, I believe mime outer friction ring started loosening whenever I had the lens in my bag with the hood attached to it (albeit inwards, facing towards the camera). Lessons learn't although it is apparently a common problem with the 100-400.
Is it worth all the hassle... maybe a 70-200mm F4 and a 300mm Prime would be a good alternate to the 100-400mm.
Thanks chaps for the input!
Dave