This is what I would do to diagnose a no spin problem with a running motor.
I would remove the cabinet and jump out the lid switch harness.
Then I would put the washer in the spin cycle and look to see if the clutch is spinning.
If the clutch is spinning then everything before the clutch (motor, motor coupler, tranny) is all ok.
So then I would suspect the clutch slipping, drive block stripped or something between the inner basket and outer tub keeping it from spinning.
If I put it in the spin cycle and the motor runs, but the clutch does not spin then I would inspect the motor coupler first and then the transmission.
If I found everything to be ok, but questioned the tranny I would remove the tranny and turn it both direction by hand in place of the motor turning it. If the tranny is ok you will see the shaft agitate when you turn the tranny one direction. Then when you turn the tranny the other direction you will see the clutch spin. If the tranny turns in both directions chances are it's ok.