We live in a 1950s ranch in New England. The bathroom is small and has a Nu-Tone fan, probably 15-20 years old. It ran perfectly fine until we had blow-in cellulose insulation added to the attic. Having only lived here a short while and never spent a great deal of time up in the attic, I can't recall if the ductwork was bendy or rigid, and now it is buried in the insulation. While I appreciate this is the right way to run the ductwork (that is, under the insulation rather than on top of it, as it was before), I am concerned that the fan has gotten crazy loud since the stuff went in. Any ideas? Might the ductwork have collapsed, or is the motor just aging?