I'm having a bit of a problem with the valves on my trumpet (an older Bach stradivarius). Apparently, the casing needs to be replaced. I've had problems with the 2nd and 3rd valve coming up slowly while I'm playing, especially if it's a slower piece and I have to keep the valves down for longer notes, etc... and it's fine, everyone I've talked to has told me it's definitely worth it to get the valves worked on even though it's a bit pricey.. the thing is I have an audition coming up soon, and I would not have it back in time. Is there anything I can do until then to help with the valves? Someone recommended using a very thin valve oil, it hasn't really helped... is there anything else I can do? thanks!