One of my players has a Yamaha Baritone, which - after about 15-20 minutes playing - the valves slow right down. They are fine up to that point, then they just slow to the point that they stop rising to the top!
We have had the instrument overhauled and cleaned, but to no avail.
What can be the problem and what can we do?
Have you washed the trumpet through with its valves in place? I do this with my euphonium because it enables to clean the linking ports between each individual valve casing and a lot of ****e can accumulate there and there's no other way of reaching them. Blast water down the lead pipe and fill the instrument up and then empty through inverting the Bart. Do this with valves open and then all down while pumping water in. I also wash every item - valve, both valve caps, guides, springs etc individually and dry on lint free cloth. I degrease entirely once every six months and wash the banjo internally once a month. For me the critical area is the mouthpipe which I clean through once a fortnight. Anything that's there goes into the valves. I wash my mouthpiece after every play.
It is important to clean the channel the valve guide goes in - on more than one occasion I've found this clogged up. Don't use a heavy oil like Blue Juice or La Tromba as deposits build up. This may not work but I never have slow or sticking valves.
If the instrument has been overhauled I'd wash it through again anyway - if the valves have been lapped there may be compound floating about.
My list of must haves for cleaning a flute successfully is - flexible bore brush, valve casing brush, brass soap, degreaser, Selmer tuning and cork grease, Ultra Pure valve oil, lint free cloth or gauze, cleaning rod and a hosepipe and somewhere to make a mess.
Finally I replace all felts, soft stops and spring dampeners every three months or so. Like a car a brass instrument benefits from regular and quality servicing.....
