I got the tar boards out this weekend. braided wire wheel made reasonably quick work of the sealer. I found several threads that mention using brake cleaner and other products to get the gummy residue off. but the thing I can't figure out is how to get into the corners of the tub to get them stripped before I paint.

some of the corners I can't get to with a sander and the kind-of-pointy wire "wheel" like thing I've got that's narrow can't get in some of the tighter spots. I've come this far, I'd like to make sure I get it all stripped down at this point.

I used a good old chisel (by hand, not powered). The old seam sealer in the corners simply comes off in chunks when attacked with a chisel.

Heat gun helps.

Heat gun and a painter's 5 in 1 tool.

Yeah, I used the heat gun and a 7 in 1 painters tool (it must be 2 bette, right?) so the tar is all, or mostly out. My question is how do I get the corners of the tub down to bare metal for painting?

Andy's chisel is a good suggestion for the bits of sealer left, but some of the corners have paint, or just 40+ years of crud. Generally when I'm struggling with something I find a really simply answer on here that makes me wish I hadn't spent so much time doing it the hard way!

Spot blaster. - I think that's what it's called.
Needle scalers are also a good tool

maybe a pick set with several shapes of small pointy picks. Lowes has them with 4. You get a straight pick, a 90 a 45, and a hook. All are great from digging seam sealer, etc....

An experienced torch guru, chisles+hammer, lots of ventilation, a gutted cabin and: Done in 8 hours Click to view attachment