I have a Carrier Gas Furnace and am having trouble replacing the filter, is there any where I can find a diagram on how to replace the filter? Unfortunately, the duct work is bolted to the unit. Where the filter should slide in, is the switch that gets pushed in so the unit works. The filter that should be used is 16x25x1 but it has to bend around the blower unit and the switch. This kind of makes it tough to bend it and slide it in correctly. Any ideas?