Care of Your Euphonium
Clean the valves once a week (or more if necessary). Very carefully remove the valves and the bottom caps. DO NOT DROP THEM. With the valves out, thoroughly wipe them off with a lint-free cloth. Take care to remove all valve oil and dirt. Clean the casings with the cloth wrapped com¬pletely around a casing cleaning rod. Do the same for each casing.
As you replace each valve, put a generous amount of valve oil on it and check to make sure you have the correct valve in the correct casing. The number one valve is always closest to the mouthpiece. Most valves and casings are also marked with numbers. Line up the valve guide with the slot inside the casing, replace the valve, and screw down the cap. Clean out the bottom valve caps and replace them.