When it rains, water builds up in the back, passenger side foot well. Did some research online and it seems to be getting through the pollen filter. Unfortunately i can't get to all of the nuts to get the filter housing out to put a seal around it. So first, am I on the right track as to the source of the leak? Second, if sealing is the fix will it cost me an arm and a leg to have a mechanic do the work?