Had a real 'oh no' moment with a Canon AE-1's shutter curtain in the shop yesterday
The curtain was sticking halfway, and I realized the old foam light seal had turned to goo and was gumming it up. What's your go-to solvent for cleaning that sticky mess without hurting the curtain material?
I've actually had bad luck with alcohol on foam residue. It can sometimes smear the goo instead of lifting it. My shop uses a tiny bit of lighter fluid on a microfiber cloth, which dissolves the sticky stuff without leaving a stain. You have to be really careful and test a hidden spot first, but it works better for me.
Read a forum post once where someone swore by naptha for that exact problem, seems similar to what @the_susan said about lighter fluid. You gotta be super gentle though, that curtain material is no joke. A barely-damp cotton swab is the way to go, dab don't rub. Let it sit for a second to break down the goo before you wipe it away.