Kenmore washing machine making high-pitched belt/motor noise, but no belt?

My Kenmore washing machine (model 110-20722-990) just started making a loud, high-pitched whirring noise on the spin cycle. It kind of sounds like somebody just turned on a conveyor belt.

The noise becomes more high pitched depending on the spin-speed setting (but is always the same pitch within that setting whether it is speeding up, slowing down, or at full speed).

It spins and drains normally, but I am afraid of damaging the machine if I keep using it.

Can anyone tell me what part I need to replace? I'm guessing it is the motor, but I'm hoping there is a cheaper fix than replacing the whole thing.