Got the new one, got it on, put the snap ring on with a new set of snap ring pliers I bought. Started it up & when I got underneath, the ring was spinning. I shut it down & popped the ring once more & watched it seat perfectly. But the damage was done already. It's leaking badly.
While spinning, the ring had sheared off a TINY TINY sliver of the rubber part of the seal. It was such a tiny piece that I can't imagine that it matters.
I guess I get to take it to a shop and let it sit over the weekend. I'm already $84 in the hole...
I'd try once more if I thought I had a foolproof method. I'm getting pretty quick at this.