The washing machine only tries to cross the laundry room during the spin cycle

Our washing machine has developed one dramatic habit: during the final spin, it shudders hard enough to move several inches forward.

It does not happen with every load. Towels are the worst, bedding is unpredictable, and ordinary clothes usually finish without trouble. The machine is in a first-floor laundry closet on a hard floor. It is four years old, and this behavior began after we pulled it out to retrieve a sock and clean behind it.

I first blamed uneven laundry, because redistributing a heavy load sometimes helps. Then I noticed the machine no longer sits with the same gap on each side. One front corner also rocks slightly if I press it when the drum is empty. I have not opened the appliance or adjusted anything beyond checking that no hose is stretched or visibly leaking.

My partner wants to buy anti-vibration pads immediately. I am reluctant to add a product beneath a machine that may simply be sitting unevenly after we moved it. Pads could reduce transmitted movement, but they could also disguise the clue that something changed. I would rather identify the basic setup problem before shopping for an accessory.

The plan is to stop using it for heavy loads until it is assessed, record one safe normal cycle from a distance, and compare the installation instructions with the current position. If the machine keeps walking, makes a new grinding sound, leaks or cannot remain stable, we will stop and arrange service rather than trying internet repairs.

What observations would be useful to a technician without encouraging us to dismantle anything? Does the fact that it started after being pulled forward make placement the first question, or can that timing be a coincidence? I am looking for a careful diagnostic sequence, not instructions for reaching under a running appliance.