Diagnosis
The washer isn't reaching high spin speed, or it's canceling the spin due to an "unbalanced load" error. On these models, a failing lid lock switch can cause this—the machine thinks the lid is open during spin and slows down for safety.
How to Fix It
First, run an empty load on the "Drain & Spin" cycle. Listen closely. If it attempts to spin but sounds labored or stops quickly, it's likely the lid lock. Test/replace the lid lock assembly as described in the first fix. Also, check that the machine is perfectly level front-to-back and side-to-side; an unlevel machine will fault out on spin.
If That Didn't Work
If the motor hums but nothing spins, the drive belt might be broken or off the pulley. Unplug, tilt the machine back (put a board under the front feet first), and look underneath. The belt should be tight around the motor pulley and transmission pulley. A broken belt will be obvious.
Heads Up
Never try to bypass the lid lock by taping the switch down. The spin cycle is dangerous if the lid can be opened. The machine is stopping for a reason—find and fix the actual fault.