Dude, you should have asked me first. I use thin adhesive back sheet foam from Michael's--like a buck for an 8x10 sheet...
Originally Posted by hpulley
Get a popsicle stick or any other small piece of wood and cut it into chisel shape. Make several. Use a QTip with some isopropyl to moisten the old foam. Carefully scrape it out--as much as you can. Let it dry and go back for more--remember you're removing both foam and adhesive. If you need an online anatomical photo of the RB back, I'll send a link. The really critical seals are at the hinge and clasp of the outer shell and the RB adapter surface that meets the back. The foam in that square channel surrounding the film gate is a critical light baffle. Let me know if you need any help.