If you have trouble getting your Grafmatic into the tighter space on the spring back, you might try this trick. Like David said, it will usually work, although it's a tight fit. Every camera seems to be slightly different in this regard regarding how far you can pull the back out. On mine I had to loosen the spring screws a little to get it in.

http://lommen9.home.xs4all.nl/holders/page2.html