I filled up my EFM 520 for the first time since getting it into position and I found some of the tubes in the back leak. I'm not sure what they're called but they're the tubes that the flue gasses travel down through to exit out the flue pipe. Just by removing the rear plate and sticking my head in there it looks like there have been some holes rusting in there from sitting. From the looks of it I have to take the boiler off the stand and cut out the plate the tubes are welded into from the top and bottom and replace that section. Is there an easy way to do this or has anyone done this before? The metal tubes look pretty thin so I'm assuming this happened on a number of these furnaces.