This is a little late, I don't know if anyone said this yet.  It is my
understanding that if your ferret is deaf, you keep the deaf ferret, and
get a credit at the store to buy a new ferret.  You don't need to euthanize
or return the deaf ferret.  I think someone on the FML had this very
situation, and that's how I know the procedure.  Correct me if I'm wrong...
 
Amy & the brat pack ;O)
[Posted in FML issue 3254]