Hold the fort! It's a good thing I read the posts on this board. All this time, I was pushing a button like is on all other PTO connections I've used. Apparently, with the statements here, all I need to do is pull back that ring, line up the splines and slide it onto the PTO shaft. "All," I say, "all I need to do." I'm not sure it will be as easy as it sounds but maybe that's why I've had such a hard time re-attaching this mower. The ring does not stay "cocked," for one thing. As soon as I start to slide it forward, the ring goes forward but is not attached yet.
All to say, I hope you get it on!

Oops...it's off in this case.
TG