Have run into this problem several times: upon rolling up the driver's window there is a gap that allows some air to swoosh in at speed. If I sort of push the window up as it rolls up the gap will close somewhat, there is some play. The FAQ says to bend the track back but that hasn't helped. The regulator seems fine, I assume the only element there would be the pivot point which if worn would cause play but this is not the case. The rubber guides don't seem excessively worn either.