I have exhaust vent troubles in all my bathrooms. In the powder room bath on the first floor the previous owner had squirrels getting in thru the wall cap. His solution was to replace the damper with a screen. Really dumb solution because now the bathroom is hot or cold depending on the season. Is it possible to just install a new damper and not replace the whole vent wall cap? The house is aluminum sided. I really hate to disturb that siding. Plus, I doubt I can ever get the new wall cap to be as leak-proof as the original wall cap. Thanks.