Your tumble dryer needs to stand level and balanced on its feet in order to function properly. Try rocking the appliance from side to side or back and forth. If it’s rocking a lot, your flooring may be uneven or there may be a problem with the adjustment of your appliance’s feet. Use a spirit level to check its balance.
To adjust the feet, reach under the appliance and find the lock nuts on the feet. Loosen them and turn the feet clockwise or anti-clockwise, until they’re firmly in contact with the floor. Tighten all lock nuts again by hand.