First of all, the bearings rarely go bad. It'* usually nothing more than a $30 coupler. That fix can happen for under $100 total in 4 hours.
Secondly, bad coupler or bad bearings will have no effect on performance whatsoever. Only noise.
Let'* properly diagnose yours first, then we'll let you spend some money.
Take of the SC belt and grab the SC pulley. Wiggle it clockwise/counterclockwise fairly quickly. Hear or feel any slop? If so, that'* the coupler.
Now wiggle it up and down, side to side with no rotation. That would be a bearing check.