pbromaghin
Subscriber
Actually I don't think it does use foam ! The C330 uses threaded posts built into the body to adjust the height of the screen whereas the C33 uses "shim washers on each screw for the focusing screen. If those were missing or put in wrong, you would have the problem you describe. " (see here).
FWIW I found you can purchase a C33 repair manual from here. Double check with them it is for a C33 (as per the image) because it appears incorrectly listed as the C330. It certainly isn't cheap, they list it for £26.95.
EDIT: Just found it cheaper on eBay here. for US$19.20.
Yup, that 2nd listing is the one I saw. I just have to get my wife to sit down and do the Paypal thing. I never use it but it's all that guy will take.