I've just looked at that tool at the Micro Tools site and I might go ahead and get one. However, I'm not sure of its application in this case. An important point I failed to mention earlier is that these screws are countersunk down into the plate that forms the inside face of the film magazine. The screws are flat topped, and when completely seated their top surface is just barely below the face of the plate.
Originally Posted by John Koehrer
So, in this case perhaps the left hand bit...?