Hi all, I have an extremely noisy cabin heater fan, I'm guessing its bearings are gone...though sometimes it's quiet...I've tried running it at full speed, then off then on again etc in case I needed to clear a leaf etc..also tried running without the filter in case that was the issue, but to no avail. So I'm guessing I will need to change the fan. Before I attempt this, has anyone else done it? Any tips?