loud

We're all used to getting spam emails... frequently from Nigeria informing us that we were selected to receive a huge inheritance from someone dying of some disease, etc. etc. etc. Today I got a letter with an attachment :o and of course was suspicious right away. Title of the email was...

Got a couple of super nice used AC 110s the other day.. we're talking relatively new and pristine. One of them is a bit loud though. I figure I'll let it run a couple of days to see if the mulm it picks up quiets it a bit. Any other ideas besides swapping the impeller for a new one? I...