Well, it took a bit longer than expected, but I finally received my two new mags. Both function just fine out of the box, but I only cycled 5 rounds from each one without firing. I expect they'll be fine.
The followers still like to tip a bit, but nothing like the one I got with the rifle, which had that broken follower.
Speaking of, I just turned it into a "bob sled" single shot mag. Didn't get much time to fiddle with it before my next range trip, so I had to do something.
I disassembled the mag, no floorplate, no spring or follower. Turned it upside down and dropped in a round and then the follower. Then I gently clamped it in a vise. The object being to simply hold the mag upside down with the round resting on the feed lips and the follower resting on the round. Then, with the mag upside down, I carefully filled in between the mag walls and my cheesy homemade follower with rubber cement. Would have used JB Weld or something else, but rubber cement was the best I had.
I let it cure over night. Next morning I was able to slip out that round, and then I ground the feed lips off so that they wouldn't interfere with dropping one round on top of it at a time. Smoothed the edges down, and it was good to go.
It's a cheap, nasty looking piece of redneck engineering, but it functions exactly as intended.