i tried all the above tricks i redisgned the frame mask sanded all the parts, foam to tension the film but none of these fixes worked.
the reason the holga scratches film is due to the way you hold it when you wind the film
you probably are holding it with your fingers wrapped around the front - back of the camera ,like a slr.
dont do this hold the camera between thumb and fore finger,thumb on the bottom and fore fiunger on the top, then wind the film without touching the back
guaranteed to work as any pressure on the back of the camera will scratch your film every time