That sucks. I just replaced the impeller on my fX6. You have to buy the whole kit in order to get the replacement bushing that sits at the bottom or back of the motor. Do you have an amp claw? you could always pull the amp draw to see if its too high.
We recently had to deal with the same. the impeller housing was too worn for the impeller to spin properly. Not fun. I wish I could help, but our only "spare" is probably not in any better shape than what you're working with.