you cant tighten it and axel barrings for pivot works are 32$ for a set of barrings and seals.. I ususaly wait till might get about a half inch of play int hen them i replace them
Is the play up and down, forward to back. or is it side to side (left to right) If the play is only side to side then its not your bearings, its the axle nuts. If the play is forward to back and up and down then its your bearings.
"IF" it only moves side to side a little bit, something is loose. I highly doubt it though. If it moves up and down, and/or front to back replace them now. I rode mine a little when I knew they were bad, and all the bearings ended up inside the sleeve and destroyed it.
Just replace the bearings now, their cheap, and I've seen it a million times, people wait until their bearing carrier glows red, then their like oh **** somthing wrong.