These are the little feet on the bottom of your machine. The originals might be worn out or missing. They often are.
Carefully lay your machine on it’s back and inspect the rubber feet. These are the cushions between your machine and the table. If they’re not perfect… replace them. Be sure to scrape all the “old feet” off of the mount before installing the new feet. This will become clear after you inspect the posts which hold the feet onto machine.