I tried to fix the latch of my SX-70 with a bit of paperclip and epoxy resin – it was less than successful! However I’ve found a guide for repairing it properly here: http://www.chemie.unibas.ch/~holder/latchjob/index.html
As my Impossible Project film has just arrived (from Korea!) I thought I’d best give it a go. Hopefully I can pick up a spare latch from somewhere 🙂