Sorry Jonny, 2 or so years ago I bought the last spare F100 back door from Nikon Canada. Problem is that plastic used for the door is brittle and teeths are easily broken. Unfortunately plastic does not age well. I think most of the F100 have this problem and you need to replace entire back door, not just broken teeths. So if you buy used body to cannibalize it and fix yours, you have to watch out for this problem. You can check with Nikon Canada if by any chance they got more of them. Good luck!