most likely the impeller that is defective. impellers for the aquaclear run around $20 depending on size. some pet stores will carry them. you can usually find used aquaclear filters on CL from $20 to $50 used.
Sometimes impeller sucks in grain of sand or something hard like that in the shaft and then that object can grind and damage magnet badly to the point where it will start making noises or eventually stop working. Pull impeller out and see if there is any damage on magnet. It should be nice and smooth. Also clean shaft with brush and make sure that there is nothing inside. If magnet is damaged, replace impeller, but remember they can be pretty expensive. Sometimes the whole new filter would be only few bucks more than the impeller itself.
So I say to her……There is plenty of stuff at the house for the baby to eat!!!! I REALLY need this fish……
how can I tell whats wrong with my filter. The filter itself is old but runs. the impeller does slide into motor and magnet works, but it makes alot of noise. should i replace the whole motor or just impeller? Thankyou for any help as i dont know much about these things.