I didn't mention that I have RTFM and it says to throw away first gear and bearing if clearance is too great (over .4mm) but it seems that would be because of parts wearing down from the friction as they spin at different speeds.
I checked the thrust washer against a new one from MC and they felt exactly the same.
I got a new 1st gear spacer and checked that against the old one and it was a hair worn but just barely perceptible.
I have been cranking on the rear bearing and that has helped get it to maybe .65mm but still out of spec. I'm a little scared to crank much harder in my press
That leaves the first gear itself as the problem, which is possible, but with a good wash it would be hard to tell it from a new gear.
I have 2 R154s on the bench and one has almost no slop, which is preferable, and the other has around .3 something which is noticeable but still under spec. And the one with the slop had already been rebuilt so probably over 200K miles.
I'm not getting how an AX15 with 140K miles, barely appearing to have been used, let alone abused, could have this sort of problem.
