I know this question must have been asked before (probably several times) but I couldn't find it.

I have a Yashica FX-103 that needs new light seals and mirror bumper. I've replaced light seals before so that's no problem. I do have a question about the mirror bumper...

How close is the tolerance on these things. The reason I ask is that the foam that I have is not the same type of foam or the same thickness as what was originally on the camera. The thickness is pretty darn close, but not exactly the same. I have craft foam (like some use for light seals). Would that work for a mirror bumper? I also have some felt left from my light seal replacement on my electro 35. If the craft foam won't work, would the felt be ok?

Thanks for helping out a newbie.

Ed