I hate to sound stupid, but how can you tell if the equalizer button(s) are still in place? I have a lot of endplay in both axles in my 8 3/4 rear end. Plus something strange..there are adjusters on both axles, left and right, for the endplay instead of just on the right side. These are aftermarket axles with small bolt pattern.
With two adjusters, I'd turn the LH adjustment nut so it's flush with the retainer plate face and then do all the adjusting on the RH. Just make sure you install lock tabs on both sides or the adjusters will move.