If they are used, they are extremely well cleaned. They are in sealed boxes. They certainly don't appear to be used. Doctors Foster and Smith have a fairly good reputation from what I know, and they certainly have been good about trying to take care of the problem. They've now sent me 3 of the 2078s. My house is starting to look like a warehouse.
The rattle has gotten worse as the night has gone on. Not as loud as the first one (yet), but it does rattle. Clack might be a better word for it.
I'm beginning to feel like this is operator error, but I've been setting up filters and tanks for years (well, decades). I just can't believe the problems I'm having with these 2078s. But if there are any tricks to setting them up, please let me know. The Eheim manuals have always left something to be desired.