Clean the tuba with hot water. Unscrew the mouthpiece from the tuba with your fingers if it is the only part that needs repair. Rinse the instrument thoroughly by rubbing your hands on the tuba while running it with hot water.
Dry the tuba with paper towels and identify the dents that need repair.
Remove the guard of the tuba, or its surrounding cover with your fingers. This will allow you to get a clearer view of the dents on your instrument.
Spray furniture polish on the dented surface of the tuba.
Run the magnetic dent removal device on the tuba, allowing the magnetic ball inside the shield to pull the dents forward and bring your tuba back in shape. Do not rub the device too hard to avoid scratching the tuba. Do this for about 3 to 5 minutes, or until all the dents have been repaired.
Reattach the guard of the tuba and start playing the instrument.