Hasselblad (old non A) 12 film back loading?! How to?

[felipe]

I bought another one
It's a late 500c with a brightscreen proscreen, but the back is a non A back with a big hole in the middle (to be able to see the marks on the back of the film)

I have never handled one of those, only the A12 backs, and after wasting one roll when trying to load it, I thought I do need some help...
So how do you do this?

Thanks a bunch,
Phil

 

[felipe]

[bumetybump]

anyone? puhlease!