Originally posted by dcshooter The felt is a superior solution and used by lots of reputable techs
My Exaktas have some sort of felted stuff as original equipment mirror bumpers with doped yarn for light seals. Eric Hendrickson has used yarn for light seals and foam for mirrors on the CLAs he has done for me (Spotmatic II, SV, and KX). My Soviet rangefinders all have yarn light seals. I asked my local repair tech about it and he said they all work.
As for the OP's camera...perhaps a CLA is in order, eh?
Steve