Yeah, Neal, I was hearing the same thing. I'd pull the transflow out, clean it, plug it in, and it would be quiet. Put it back in the stove and it would screech like a banshee. Tried loosening the screws, riveting it in, even tried a layer of ceramic fiber as a gasket to eliminate metal-to-metal. Nothing would stop the screech once it ramped up to high speed. Finally, after I posted about this, it died completely...feels like the ball bearings are shot. Could be that the housing was getting torqued somehow and caused the bearings to wear.
The wife is actually thrilled with this makeshift solution...it really is washing a lot more heat off the stove, and because of the lower rpm it's a LOT more quiet. I keep thinking that it can't be this simple, but I'm having trouble seeing a downside to it!