I'm helping this kid in the neighborhood who was never taught how to clean her trumpet - tells me about her school music teacher. She in grade 7 and bought her trumpet about a year and a half ago. I asked her when was the last time she put slide grease or valve oil on the tuning slide. She told me with a resounding "Never". Anyway, the tuning slide feels like it's fused to the trumpet. Also the valve caps are all stuck, and so do the third valve and third valve slide. I used some WD40 on all stuck parts and they still refused budge. I tried using mallet to soften the crude buildup which didn't work either. Since I heard that WD 40 is useful for softening rust and cruddy metals, I told her to spray on the parts regularly until the parts are ready to come off as they should. I don't know if this is going to work but I hope it does. This is not so expensive trumpet, so giving it to a specialist for repair would cost about 1/2 of the trumpet. Anybody has some advice, I'm all ears. Thanks for your time and looking forward to hearing from all of you.