Stuck valves on a baritone horn indicates that the instrument needs to undergo an extensive maintenance procedure and possibly a professional valve repair. Choosing the correct process to repair the valves on a baritone will require a careful evaluation of the horn to check for any dents or scratches to the outside of the horn. Usually baritone horns just need a thorough cleaning, since the valve casings are reinforced and fairly resistant to damage. Damage to the actual valves is rare and will require professional assistance.
Remove the valve tops by turning them counterclockwise. This will free them and allow you to remove the valve caps from the valve stem.
Unscrew the valve caps that attach to the valve casing by turning them counterclockwise. If the caps seem to be stuck, you can wrap a cloth around the valve cap and use pliers to gently twist the valve caps off.
Pull the circular felt rings located underneath the valve caps up and over the valve stem to remove them.
Grab the valve stem and attempt to remove the valve from the valve casing by pulling up on the stem. If the valves do not move, pour a few drops of dishwashing liquid around the sides of the valves. Let the soap drain through the sides of the valves for about five minutes and attempt to remove the valves again. If the valves remain stuck, rinse the horn with cool water and take it to a professional repair shop.
Check the inside of the valve casing with a flashlight. Look for any scratches or dents that may be preventing the valves from moving freely. If you find dents, have a repair shop buff the valves and remove any dents in the valve casings.
Place the valves in a tub of 5 gallons of water with 3 tbsp. of dishwashing liquid. Rinse the valves thoroughly, clean them by using the valve brush to remove any dirt or grime, dry them with a towel and place the valves aside.
Submerge the horn in the tub of water. Use the valve brush to clean the inside of the valve casings. Brush until you are certain that all of the grime has been removed.
Apply oil to the inside of the valve casings, place oil on the outside of the valves and insert them back into the valve casing. Place the circular felt rings back on the valve stems, put the valve caps back on and screw them into place. Finally, replace the valve tops.
Press down the valves and remove all of the slides before cleaning the baritone. This will ensure that pressure doesn't build up inside the baritone.
Be very careful using tools to repair your horn. Always place a cloth between the tool and the instrument to prevent damage to the horn. The alloys used on baritones are extremely delicate and can easily scratch and suffer damage.