Washer does not agitate, squeals, burning rubber smell.

My Maytag washer will not agitate. It fills, drains, and spins fine. When it comes to the agitate part of the cycle, it makes a low humming noise ( I believe this is the same noise as it normally makes, only minus the sounds of swishing water). After a while, a squealing noise starts, and I can smell burning rubber. The noise is just like a loose belt in a car. The loss of agitation was also progressive, from a ‘weak’ wash, to very minimal movement of the agitator, to complete failure to move, along with the other symptoms.

I checked the belts and they are fine, and there is no oil or liquid leaking. With the belt off, the large central pulley underneath is hard to turn counter-clockwise, and moderately hard to turn clockwise. There is no grinding, rumbling, or clinking noises. The tensioner moves freely.

I might guess that perhaps the transmission has become clogged or the grease has become sticky, or something has wound itself around the parts somewhere?

*This is an edited repeat of an earlier question, but with more details.

Any help is appreciated.