if anyone's still scratching their heads..i was able to fix this today without a new starwasher. i just pounded the stock ones in further. no popping noise, no movement.
it was making a little bit of noise when the car was new, but lately (after 3yrs) i could sort of almost feel the seat bottom shifting just a hair so decided to fix it.
check tsb on what part is involved. basically it tells you to get 2 new starwashers which are like $2+ each and where they go.
ck service manual on how to remove the seat and the dials. you can do the work inside the car so you wont have to undo the SRS harness (no need to unplug battery which is a good thing).
total time... probably 1hr tops including vacuuming and nourishing the plastics afterwards with Prima Nero.