Yep, that thing's making a racket! Most likely the motor bearing. Outside chance it's something in the fan so check that but sounds like a bearing to me. What happens is the seal leaks for quite a while before you notice and water passed through to the motor bearing. After a while the bearing corrodes and then makes this noise. You can replace the bearing but it's a real pain because the long skinny bolts that hold the face plate on are corroded into the end plate of the motor so they break instead of unscrewing. Then you have to drill them out and re-tap or re-bolt with all-thread. You have the same issue with a retainer bolt in the bearing housing. So sadly this normally means a new motor. Motor repair shops normally won't touch it since it's easy to lose money on it. Wish I had better news. When you get the new motor consider removing the long bolts one at a time and add some anti-seize liberally. This makes the motor repairable in the future.
I hope this is helpful.
Chris
