Call ER and see what they are willing to do. I've heard a great story about a guy locally that bought an old ER from ReefCentral. When it arrived the impeller was junked out. The guy made a post on RC asking if anyone had an extra Needlewheel around for a Sedra as his did not work. Seems the fellow at RC wanted to show how nice their customer support was and offered to send him a new impeller for free even though the unit was bought used and out of warranty. It's that kind of customer support that keeps me buying their products.

And as to being down for a few days, I don't understand how. You order the impeller, pay $55 and they ship you a new one. You replace the defective one with the new one the day it arrives.