Kenmore 110.28002010 drum does not agitate or spin.

ok, so here is the problem. PS, this is second hand from my niece. You load the cloths into the washer and shut the door. It locks and fills with water.
it goes through the wash cycle (but it doesn't sound like it is agitating). Then it goes through the drain cycle (you can hear the water draining). Then while it is in the spin cycle (it doesn't sound like it is spinning) the door unlocks before the spin cycle finishes. the cloths are soaking wet and doesn't seemed like they moved.

Is there a diagnostic to test the motor?
I read about a motor coupler, could that be it?

thanks jack