I have one of the last engineering change (61-3).
I haven't figured out why they quit making them - unless the first two iterations (61-1 & 61-2) were a lot worse than the last version - and by the time they got it right the gun had a bad reputation and wouldn't sell. I know that kind of thing happened a lot with American products in the 70's and 80's.

Mine took a little tweaking of the magazines to get it to work 100%, but with the original magazine it has functioned at least as well as any of my other 22 semi-autos, and better than some. It cycles reliably and doesn't seem to be any pickier about ammo brands & bullet weights/types than any other semi-auto 22.

Maybe I just got lucky and got an exceptional one....