Doesn't sound like one of our units as the solar panels are integrated into the top of the solar fan with ours. If I had to bet it would be that the fan still utilizes a brushed motor design and they are wearing out. If it's one of the original roof vents and someone put a fan inside of it we won't be of much help repairing it. I believe that was someone operating out of the flea market but I haven't seen him around in years. It was more of a DIY project and parts are hard to track down or discounted altogether. If you can get a picture from the ground and email it to
sales@thesolarguys.com we can try to identify it for you. We could disconnect that fan which would turn it back into the orginal static vent. We could also install one of our brushless solar fans on your home if you wanted more ventilation. Hope this helps.