'Ensure any sharp metal burrs are removed from the edges of contacts. A metal file might be required.

Cut a piece of coarse emery cloth roughly 3x the width of the contact (normal sandpaper is not recommended as it can leave deposits of other metal types on the contact surface)

Fold the piece of coarse emery cloth, and place it between one set of contacts at a time. Apply gentle pressure to the contacts and sand evenly between the two surfaces.

Repeat process above using coarse, medium, and fine emery cloth to ensure a good connection.

Close the relay by gently pressing the plastic top bracket. Ensure an even and flat connection between the contacts.