Just an add on, the original tool for removing the mast jacket
busing had a tapered thread that was forced into the cup then
a slide hammer was used to remove it.
I made a quick copy of it once a few years back:
http://www.pbase.com/dennygraham/image/121665549

A lot of them will simply just pry out and I've seen some that
you could have lifted out with out any tools.

dg

Denny G
Sandwich, IL