Intermittent crankcase pressure issues

Well, give teringer credit for the big clue here. And BTW, use a feeler gauge thickness that just slips in, but is not tight. If you have .021 now, then with a new ring, it's gonna probably be .004"-.005".... stock is .001-.003". Not sure if the KB's have a bit wider groove or not, or should have a bit more, so you may have some slight to modest groove wear. Really worn grooves have more side clearance than that.

See if you can figure out how deep the radial groove is up just under the ridge area; that is probably due to the ring twisting as the piston passed TDC and digging into the wall as it started down.

It's gonna be a lot better regardless, and for a short life, 5/64" rings beats running the thin rings that were in there LOL. And yeah, it just takes one little thing..... At least now you know what proper ring side clearance is now, and will spot this problem by eyeball in the future..