Bad secondary vaccuum units??

[92ShoOff]

Hey everyone. I just received my big bore butterflies and I noticed something... when I close the butterflies with my fingers and quickly remove my finger from the butterflies to let them flip back open rapidly I hear the vaccuum thing make noise as if something is loose in it. I tried the same with my original secondaries that were on the motor and they don't make that kind of noise when you let the butterflies flip back open. You can hear the air getting pushed out of the vaccuum housings on my BBB's and on my old units, but something just sounds funky with my new ones.

Is this normal on older secondaries, or should I swap out the vaccuum units on my new butterflies with the ones from my old butterflies? Thanks in advance!