http://cesarigd.club.fr/photoe2b.htm

That's the link I found handiest the first time I had any problem with jamming - The tool that Hasselblad (And other 3rd party producers) make for fixing the soft jam can easily be made yourself with the right sized screwdriver and some shrink wrap - The shrink wrap ain't essential, but comes in handy if you don't want dents inside your camera or the screwdriver slipping past and putting a nasty little bit of damage into your glass!

A hard jam requires a bit more work (As I found out). Having a screwdriver or multitool in your bag can be a lifesaver if any situation arises!

If you're morbidly curious, it's worth popping open the 'bonnet' and seeing how it works!

Cheers for that Martin, very handy to know!