I don't think I have ever really heard for sure of a closed pressurized boiler, corroding through like this from water issues. My old one looked brand new inside after 20 years, when it was originally filled with well water that is generally high in iron & manganese, and a little bit low in PH. Actually, it looked better than new inside, it had a thin coating of black stuff all over that seemed as if it was offering protection - looked like flat black paint. If air was regularly getting in somehow, that might change the water on the beans. Or, if there were naturally occuring salts or something like that in it. Really curious as to what happened here - not sure if we will ever know though. I'm pretty sure I wouldn't pay those quoted freight charges, but I might load it up & make the drive myself if I were the OP. Wonder if the return protection pump stuff if installed was actually working right? Although I know nothing about Econoburns & their setup for that or how its controlled. If the pump wasn't pumping when it was supposed to be, that wouldn't help, creosote & corrosion-wise. Might also set up for improper flow inside the boiler & possible hotspots/cavitation inside?