Remove the roller door from the door frame. You may have to lift the roller door out of the track and over the frame, or unscrew the stationary door from its frame and then lift the roller door out and lay it down. The rollers are at the top and or at the bottom of the door. Unscrew the rollers and remove them. Clean them in a pie tin, applying turpentine with a wire brush and wipe clean with a rag. Examine the cleaned roller and coat them with WD-4, silicon spray, or penetrating oil. Reassemble the parts in reverse order, and then clean the track before reinstalling the door.