Why does the tub not spin with a full load?

Why does the tub not spin with a full load?

The tub will spin automatically during the spin cycle with a light load, but if a full/heavy load, like when washing towels, the tub will not spin by itself. Will start to spin if open the lid and give the tub a "push" to start it spinning.

ANSWERS:

@ghkroupa this behavior could be caused by a bad clutch. Take a look at this guide. different model but same idea. Let us know what you find.