I just purchased a brand new Generac 6729, actually it's the Honeywell 7063 which is the same model. I got a smoking deal on a new one on ebay so I purchased it. I'm not the biggest fan of these backup units as I had one before at my other house and it kind of nickel and dimed me. I want to keep some spare parts in stock just in case something breaks. I don't mean oil and air filters but important parts that take time to get. My other concern is something getting discontinued. I believe I had to put a computer controller on my old one. What parts are the most prone to failure on these units? I'm not too concerned on spending money on parts as I rather be prepared. I'm the kind of guy who bought an extra furnace when I built my house so I always had what I needed to fix the one heating the house, yeah I did that.