Thanks guys for the help so far. Incidentally, is anyone reading this from the Derbyshire or Nottinghamshire area of the UK who I might be able to visit with said camera just for them to check it is actually jammed and not me being stupid? It will be a great way to have a brew and talk about Hasselblads!

Can you actually name this screwdriver so I know what to search for or provide a link to buy it from? Many thanks