Mamiya C330 focus screen issue

I was very fortunate to get both a C330 and C220 in a trade today. The 330 is in excellent condition but needed cleaning. I used a blower to remove dust from the focusing screen, but later noticed black specs on it. It turns out that the foam seals between the focus screen and the holder have turned to both dust and goo. I have redone light seals in many cameras, but the foam around the screen seems to be thinner. Does anyone here know where to get seals that are the correct thickness? Any and all help is appreciated. I also will be looking for a strap for the C330. Any suggestions? Thanks.

Someone can correct me if I'm wrong but my memory of the C330 screen is that the thickness of the foam seals has no bearing on the position of the focus screen so long as they are thick enough to push it up against the metal plate. A clip stops it from falling. People run into trouble with focus screen position and foam thickness once they get too thin because then they stop pushing it up against the metal, and it loses definite position. So my suggestion is: use anything that will fit without distorting the screen.