I'm sorry to say that this is potentially very bad news. The problem you describe is quite possibly because the main bearing on the drum is worn out, allowing the inner drum to "flop about", when this happend, garments can get trapped between the inner and outer drums, causing pulls in the material and stain marks as the material is rubbed hard against the rubber gasket.

To test your bearings, open the door of the machine and by putting a little lifting pressure on the top of the inner drum, attempt to rock the stainless steel inner drum up and down.

The outer drum is mounted on springs and shock absorbers, so it will rock about (and it should do this) but the inner drum should not move up and down in relation to the outer drum. There should be ABSOLUTELY NO PLAY between the 2 drums, even the tiniest amount will mean the bearings have failed.

If the bearings are bad enough then other symptoms will typically include:

A clonking noise as you lift and release the inner drum (this is the inner drum rattling on its bearings and/or hitting the outer drum)

You will have become aware of the spin cycle becoming far noisier recently and possibly even a grinding crunching noise when the machine spins.

The drum may feel like something is crunching or stopping you turning it when you spin it by hand with the door open.

A leak from under the machine, which you will probably be able to trace to the back of the machine, coming from the centre of the drum. This is a result of the failing bearing allowing water to escape through the seal at the rear.

This is NOT a job for the uninitiated DIY enthusiast as it will mean stripping the machine and removing the drum from the chassis, splitting it, removing pressed in bearings and then sourcing and re-fitting new bearings.

To be frank, the cost of a bearing set (if they are replaceable, and most are) will be about ?£20 ($30) or so. But it's a long and horrible job if you haven't done it before. I know professionals who claim they can do a bearing change in under an hour, I've done a few and it takes me about 2 hours by the time I've ripped the machine apart and reassembled it after the bearing swap. A local repairer will probably attend and swap out your defective drum for a refurbished one and then take yours away so he can refurbish it and put it back in his stock. Sadly, this will take the price up to the point where you need to question if the expense is worth it or do you get a new machine instead.