I am pretty sure those bearings in there are sealed bearings and you have to get the axle retaining ring out to get the bearing out. i know the retaining ring can be a bear to get out sometimes.i know you said 99% sure but sometimes it can fool you. might want to put your cart up on blocks,you will have to do this anyway, and get another person to operate the throttle while you try to listen for the noise with a probe, old school use a wooden dowl, just my suggestion because it would pinpoint the noise a little better and give you a better start to your repair.
