Thanks Bert. I just finished replacing the idlers and that fixed the problem! Two pulleys at $18 each !!
I only use a leaf blower to clean the mower. I've never washed my deck. HOWEVER, I usually jump in my salt water pool before mowing, and that has definitely done number on a small part of the deck, and the metal plate that the seat is bolted to. That could very well be what FUBARed the idler pulley bearings. Going forward, I'll sit on a towel when mowing.
I have wire wheeled, sanded, primed, and painted the affected part of the deck and the plate under the seat.
The bearings you refer to - "cutting out the welds" - are you referring to the spindle bearings ?