I just found the 3AA MiniMaglite that I thought I left in a motel
room over a year ago. (it was under the car seat) Two of the
batteries leaked -- the ones closest to the lamp. The corrosion
doesn't look bad. The bottom battery just dropped out easily, and I
was able to knock the middle battery out by hitting the tailcap with
a deadblow hammer, but the last one won't budge. I don't see any
way to take it apart from the lamp end. Any ideas?

I wonder if some penetrating oil would help?

Bob