Did you find out what was keeping it in place?
I have a set of axe head wedges for this very job, they spread the load evenly and don't damage the delicate alloy.
Take a look at the splines on the end of the drive shaft where it locates in the end of the crank, make sure the splines are ok, are they dry of grease?
I've just had the same thing with a Mariner 60 and both parts of the splines were dry as a nuns chuff, they two had pretty much become one. I got my hands on a bore camera to check the splines on the end of the crankshaft and all is good.
There is a place on this planet for all of Gods creatures.........right next to my tatties and gravy.