Scratches: Wax the affected area using a soft, clean cloth. Repair with a touch-up kit for urethane finishes, available from any wood flooring retailer.
Dried milk or food stains: Gently rub with a damp cloth, then rub dry and wax. Use a cleaner developed specifically for urethane finishes. For stubborn spots, scrub using the urethane cleaner and a scrub pad made for urethane floors.
Water stains or white spots: Rub the spot with #000 steel wool and wax. If this fails, lightly sand with fine sandpaper and clean the area using #00 steel wool and mineral spirits or a wood floor cleaner. Allow the floor to dry, then stain, wax, and hand buff.
Heel scuffs: Rub in a small amount of wax with fine steel wool and hand buff to a shine.
Mold or mildew: Rub with a wood cleaner using a soft, clean cloth. Use a cleaner developed for urethane finishes. If the mold or mildew lies underneath the surface finish, sand and refinish the area.
Chewing gum, crayon, or candle wax: Apply a plastic bag filled with ice until the gum is brittle enough to crumble off. (Solvent-based wax can also be applied to loosen the deposit.) Remove crayon or candle wax by placing an ink blotter on the wax and applying a hot pressing iron to the top of the blotter.
Oil and grease stains: First rub area with kitchen soap having a high lye content or saturate cotton with hydrogen peroxide and place over the stain. Then saturate a second layer of cotton with ammonia and place over the first. Repeat until stain is removed. Let the area dry and then hand buff.
Dark spots and ink stains: Try the water stains or white spots treatment. If the spot remains, apply a household bleach or vinegar and allow it to soak for an hour. Rinse with a damp cloth, wipe dry and smooth with fine sandpaper. Stain, wax and hand buff.
Wax buildup: Strip the old wax away with odorless mineral spirits or a wood floor product made for stripping wax. Use cloth and fine steel wool to remove all residue. After the floor is dry, wax and buff.