I'm sharing this experience, so maybe someone can benefit:

I went to open the rear hatch on my project westy today. It would not
open. No big deal, I thought, I'll just pop it from the inside. Installing
a new interior panel with the original project at hand, so there was no interior
panel.

I could not get the "cam" to budge! I finally had to soak the mechanism in
oil, and then use a screwdriver and small hammer to pound the latch cam
from the inside to release. Wow, that took some doing, with scratched arms
and hands!

When it finally popped, I pulled the whole corroded assembly out, cleaned
it, and oiled it. Since I had it out I also fixed the worn lock cylinder
(which is a whole 'nother subject/story).

So, the moral of this story is to make sure that latch assembly is well
lubricated if you have the chance!

Jon