wrote in message

This washer is a top loading Maytag, model A308/A308S. I thought it was
bought new
at least 15 years ago....in reality I bought it new 26 years ago...it's
faithfully served a family of 2 since
then, never needing any repairs or adjustments.

Could it be that the other belt needs tightening? The one that goes to
the larger pulley? Or is this a belt thing at all?

When I tightened the one belt, I turned all the pulleys, and they all
seemed free, no heavy drag or grinding sounds.

IIRC, there is no tensioning adjustment like you'd find on a fan belt of an
auto engine. The motor mount is spring loaded and slides back and forth.
Cold be it is not sliding. There could be weak or broken springs or, after
26 years, other parts wearing out and ready to go.

It is also possible that the belts have stretched and can no longer tighten
as needed for proper operation. They do war and stretch over time and even
though them may look OK to the eye, performance is suffering.