Perhaps the coupler between the motor and transmission is broken. If that is the case then you can just replace it with a new one, however!
Here is that part.
Whirlpool 285753A Whirlpool Direct Drive Washer Motor Coupling - AppliancePartsPros.com
The however is why did it break?
Old age?
Something stuck between the basket and outer tub?
Transmission neutral hold not working? This is most common!
If so then fix it with Whirlpool 388253 Neutral Drain Kit - AppliancePartsPros.com here is a repair video https://www.youtube.com/watch?v=ieZ5y47TAMk
The easy way to test for neutral drain is, after replacing the coupler run a cycle with water level set to small. When the cycle begins to drain prior to rinse do you hear a clunk sound and detect that the barrel is spinning with water still in the tub?
You see the neutral should allow the pump to drain the standing water from the tub, the timer will pause for a moment and then start back up engaging the transmission to spin. If that doesn't happen the weight of the water and clothes put extreme pressure on the coupler.