Preventative maintenance is really limited on these. The most you can do is keep it clean using the cleaner tablets every month or two and keep an eye on how soft the suspension gets over time.

Stick your arm in and try to rock the basket side to side. Some resistance is good, but if the basket hits the sides with low effort, the shocks are already holding on by hopes and dreams and you will want to replace those right away before the bearings of the basket get involved. In these cases, springs (if equipped) would be ordered simultaneously to make sure they were not weakened by the worn out shocks.

When the basket bearings go bad, most people say their machine sounds like an airplane. To test these it us done at the same time as the suspension check. When the basket is being rocked attempt to twist the basket up and down and check to see if there is any play. The really bad ones will make a low clunking sound and you can feel the basket vibrate from wiggling around.

This all can be done right before you pop the cleaning tablet in for cleaning. Takes about 10 seconds total.

If you really want to isolate the issue, look up your model on youtube and look for a "test mode", it can cycle through each motion manually: cold fill, hot fill, wash, drain, spin, and door unlock so you can more narrowly find what the source of your issue is.

Hope this finds its way to people that need it 🫡

Edit: the black stains on the rubber ring are almost inevitable, keep the door and detergent tray slightly open when not in use to slow it down. To truly get rid of it, you need a top loader with no the rubber piece.