Here are some of the common problems that can occur with piston valves and appropriate resolutions for them.
1. Piston Valves move but are sluggish and stick occasionally.
Remove the valves and valve caps one at a time. Clean the valve casing with a valve case brush or a soft cloth wrapped around a short cleaning rod. Clean the valve using a brush and a solution of warm water and brass soap. Dry the valve thoroughly and allow to stand for some time. Apply a few drops of appropriate valve oil and then replace.
2. Piston Valve keeps spinning in casing and do not click into place.
Check each of the valve guides one at a time to make sure they are right side up and are not broken. Use another valve as a model if you are not sure. If the guide is broken, you need to take the instrument to a professional instrument repairer.
3.The Piston Valve Instrument does not play.
Starting with the third valve, remove each piston valve one at a time to make sure it is in the right casing facing the right direction. The numbers usually face the mouthpiece. Reinstall the valves correctly and try again.
4. Piston Valve is completely stuck.
Apply a few drops of oil to the valve through the valve slide. Leave for an hour or two and then try to release by hand.