My middle Valve will stop half way whenever I push it down. The valve and the inside of the casing are both very well oiled, and I checked the casing for dents, but there are none. It could be the spring, but as far as I can tell it seems to be the same as the others (The only way I could "test" it was to pull up on the little knobs, are there any better ways of testing/comparing the springs?) Any more suggestions as to what could be the problem?

I`ve tried to tel as many peoeple as possible, but my horn did the exact same thing! The middle valve would stick just randomly and nothing could fix it. That is until I tried this new oil called "Bell`s Super Lube". It was designed by a trumpet player and repairman at the University of North Texas. I haven`t had a problem since then. Check this stuff out, it`ll help for sure - - www.bellssuperlube.com

Make sure the second valve slide isn`t bent. It may look fine, but it still could be interanlly bent, so fiddle with it a bit.

if its not oiling, the valve or the casing could be bent in which case you need to take it to a repair shop... if you live in nova scotia i suggest you take it to lane francis in dartmouth. some kid sat on my trumpet and i took it to him and he did a terrific job...cheap too!