#1 Mamiya Focus Screen / Frame fits C330 but not C330F?

I have a #1 Mamiya Focus screen/frame that fits a C330 and a C330F but the #3 screen/frame will fit the C330 but not the C330F.

Whith both frames on the table and looking at the side with the thumb screw you can see that that #3 frame does not sit flush on the table where as the #1 frame does.

Has anyone else ever run into this and does it occur with other screen/frames?

Thanks

Todd