did you happen to remove the pump?
Whether you did or not, remove it, clean the impeller well. After that, you can run the pump dry off the canister to see if the impeller spins. Hold it up right so the impeller is facing up. If it works then the impeller was stuck on something. If it doesn't, a new pump is needed. Personally, if it comes to that, just remove the impeller, stick the pump back on and hook up an external Quiet One Pump that excepts 1" tubing.