this is the closest I could get.

The brass teacher at our school has been off ill for around two weeks and is likely to be for a lot longer. I'm not a euphonium player myself, but our only player is having trouble with her instrument. She's playing a Yamaha YEP-201 and the second valve always sticks down. It presses down no problem but then sticks there and she has to yank it up, it's very difficult. So far I have cleaned out the casing and the piston, tried using a different oil (Fast oil, in case it helps) but nothing has worked. We have a concert in just over a week's time! Can anybody help?

maybe her picture is not working. try to put a new.

http://www.ornithopter.de/grafik/funktion/feder.jpg

That's great, thankyou! I'll try those two suggestions...but I may be back if it doesn't help!

I checked the plastic insert and we tried a different spring as well, but it doesn't seem to have helped. Any more ideas?

Hmm.. those are the only things I can think of.

The only other possible thing (rare) that I would see wrong with it would be the valve or the casing was bent. The only way that could be "Diagnosed" would be by a teacher or a music instrument repairer.