I don't have any specific knowledge of this model, but if the disk spins but the belt remains stationary, it has to be the drive coupling that connects them. If that coupling is a belt, either it has stretched and needs to be retensioned or it is worn and needs to be replaced. Belts are cheap enough that I'd probably just buy a new one before even digging into it.

Try squirting wd-40 onto the bearings and see if they are freed up.

If not just buy a new one as its not worth messing with.

OP: I finally got a round to trouble shooting the Sander. Problem was obvious, the drive belt was shot. Problem now is to find some where to get the belt. I would prefer to buy locally but will order in I can not find it here.

I Googled "rockwell RK7866 belt" and got lots of good looking hits, so you shouldn't have any trouble getting it online if you can't find it locally.

Thank you for the information. I will see if I can find one locally and if not I will order online.