I've just built my Gakkenflex on my first film it kept slipping and not advancing properly. So here is a quick fix.
All you will need for this is a thin piece of card or foam. I used a little piece of sticky backed foam I had left over from a seal kit I had for my Yashica Electro.
The reason for this tip is that when I put my first film in my GakkenFlex and tried to forward the film it kept on slipping off the sprocket pins and would not move the film advance wheel properly, so I didn’t have a clue if I’d advanced the film either too much or not enough.
All you will need to do is cut your card/foam to fit in between the first two rails on the back of the Gakkenflex and stick it down so it covers the sprocket wheel when the back is closed. (see the picture I’ve included)
It works a treat and also puts a little more tension on the advance so the film lies flat against the back…..
Hope you like the tip and I’ll post my first roll when I’ve developed them.