LOL, after this update we might have to change that to "Three filters, One OCI". As I stated before, I have been in contact with RP today and the person that I've been exchanging emails with seems extremely knowledgeable, pleasant, and quick to respond. While he remains skeptical that the ADBV has failed he didn't rule it out and has provided me with a plethora of data, possible causes, and even researched common issues associated with my particular situation. They are sending me a new filter for my trouble. He did not mention sending the old filter back but I'll wait until he emails me back before I cut it open. No startup noise all day on the MC filter.....