1) Quiet when new - remains quiet 2) Quiet when new - gets noisy over time then stays noisy 3) Noisy when new - stays noisy
I don't think that anyone has come up with a proven way to reverse the noisiness except by swapping out the BB and hoping that you get a category 1 unit.
p.s. Mine seems to be cat 1 (so far) - so they do exist!