Hello, We bought a house with a 25-PDVC already installed & I'm doing a cleaning on it (Pretty filthy - I don't think it was ever done). I cleaned out the combustion blower & replaced gaskets, but the manual also says to remove the burn pot & replace that gasket. The instructions & diagram in the manual don't give much help in how to actually get the burn pot out, and I don't see any obvious screws or bolts holding it in. How does the burn pot come out? Thanks!