Just a couple things, not taking sides but I just wanted to add my $.02. First, I know for fact that they have the customer rules or whatever there called taped to the front counter, at the register as well as at least one other place if not two other places in the store. On those rules it does state that there is a 10% restocking fee on all returned dry goods. But the kicker is if you asked for a replacement; had you asked for a replacement there is no restocking fee. I know this, Ive shopped there many a time and if there is ever a problem with anything Jason always does me right and gives me a replacement pump/heater/whatever was defective and at no cost to me. Thats not a 'hookup' for just me either, Ive seen him do the same thing for someone else. and lastly were you using the pump inline as a venturi? if you were, thats not what the mag 7 is designed for. You need a needle wheel pump for a skimmer, and thats why it was making the rattling noise.

P.S. Support your local LFS.