Once all the setscrews are removed, a block of hardwood and a BFH or a splitting maul should get it moving. It's probably stuck pretty tight after being there for several decades. You might also consider heating the housing where the setscrews are located and maybe squirting some penetrating oil like PB Blaster through the holes.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!