Mamiya C Series Eyelevel Prism

I own a Mamiya C330s with the waist-level, eye-level prism, and metered porrofinder.

The eye-level prism has a rattle in it. I took it apart, and noticed that the foam padding was crushed, losing its bounce. I have some similar sheets of foam rubber which could be cut to pack the gap between the prism and housing roof. It doesn't seem like there would be a focusing issue, since everything is screwed down tight.

Am I missing something? It doesn't seem like a very complicated fix.

It shouldn't be as long as you don't fiddle with the mirror or or focusing screen.

An easy fix. I had some double-face foam mounting tape laying around, and I cut a couple of strips and put in place on the inner prism housing. Then I cut a couple of index card strips to keep tape from sticking to housing. Tight as new.

I didn't have any single face foam tape in the house. So, this worked perfectly. No movement at all, and image is aligned as before.

I've used those foam wedges women (and men?) place between their toes while the polish dries.
Cuts easily and handy for all kinds of small jobs.
There are probably better alternatives however.