Most importantly...are you sure you have the rudder locked so it's pointing the boat into the wind? I do a slow tack, back winding the jib, steer the boat back into the wind, lock the rudder and ease the main slightly. Try this before reducing the jib.
Turns out that, for some reason, on the one specific Catalina 22, the rudder must be pointed straight on center-line when hove to. One instructor doesn't believe it while another says he seems to remember the same issue with that boat himself.
None of the other boats in the sailing club fleet behave that way, even the other 22's.
This past Sunday I tested it out just to make sure and, every time I pointed the rudder leeward all the way over, the spin started. When the rudders brought back to center, it stops and the boat stays steady and slows to stop.
Took a Catalina 25 out two days before that and the maneuver works as it's supposed to.
Good news is I know what to do to get the result I want out of the one vessel. Can't wait for Friday (day off from work) so I can get back out on the water.