I've noticed that when I stand the springs straight up, it seems to tilt slightly. I suspect it may cause the valve itself to grind on the sides of the casing (inside). Even if it's slight, it may be something that could add up.
Two symptoms that got me to notice this:
1) despite oiling my first valve, it still seems less responsive, as in there are moments where there will be a delay in it going back up
2) When I play certain notes (e.g. treble clef B, with 2nd harmonic group), I hear this "rattling noise". Ditto with what I mentioned above, it's a nuisance that I'd like to take care of, but it also seems like something that could add up, or be indicative of a larger problem.
Are replacements as simple as going on to Amazon, Ebay, other online music store, and just buying whatever's in "good condition" or better? Anything to look out for price-wise and quality-wise?
Thanks ahead of time for the replies!