Start by asking whether the washer shakes only with certain loads or during almost every spin. A one-time imbalance is different from a persistent installation problem.
Redistribute the laundry
One large absorbent item can place most of the weight on one side. Pause the cycle, redistribute the load, and avoid a lone heavy item when the manual recommends balancing it with others.
Make sure all four feet are stable
The cabinet should not rock when you gently press the corners. Level the washer according to the manual and tighten any locking nuts used on the feet.
On a new washer, check shipping bolts
Front-load machines commonly use transport restraints that must be removed before operation. Violent vibration from the very first cycle is an important clue.
The floor can amplify movement
A flexible or uneven floor may resonate. Do not hide an unstable base under soft foam that allows even more rocking.
Persistent banging can indicate suspension wear
If the washer is level, correctly installed, and still shakes with ordinary loads, shocks, springs, or tub components may need service.
Stop using the machine if it walks far enough to strain the hoses or power cord.
Sources
- American Cleaning Institute — Laundry Basics — Laundry loading, detergent use, washer care, and safe laundry practices.