I think I lucked out

Last fall when I bought my 620, the Previous owner said the engine ran great till it started knocking one day and he quickly shut it down. This machine sat in this fellows garage for 8 years till I came along and purchased it. Well, with our looong cold Winter this year nothing got done till a few warm weekends came where I pulled the engine out of the 620 just a couple weeks ago, and started cleaning up the chassis. Yesterday, I took some time out from my busy work schedule to "play" a little bit and started taking the 620's engine sheetmetal off so I could get to the flywheel a little better. Once everything was out of the way, I grabbed the flywheel, moved it an inch or two and it came to abrupt halt! Went back the opposite way and same thing. Whoa! This thing might have a broken crank or a bent rod I was thinking. I gently tilted the engine forward on the front PTO to check out the stator and magnets just in case things were coming apart back there and jamming the flywheel. Hmmm... looked okay from what I could see. Still, not good in my mind yet. I started to move the flywheel a little again and then I spotted my "knock"! One of the starter mounting bracket bolts worked its way out far enough to where the fins on the flywheel were hitting the head of the bolt. I ran the bolt in a little with my fingers, and sure enough, the flywheel rotated 360 nice and smooth. What was even more music to my ears was the loud sound of compression as I rotated the flywheel. This engine turns nice n' smooth, and with that compression making all kinda noise, I'm a skeptical but happy camper at this time. Being pretty wound up over this, I had to pull the heads to make sure the cylinder walls have no scores, and the pistons look okay to insure no damage from broken parts internally was done. Further investigation shows everything looks normal inside! Even the combustion chambers are pretty clean. The normal carbon deposits but no oily gunk present, and the valves look nice opening and closing as they should. I don't think there's a thing wrong with this engine other than now it needs a few new gaskets and a major cleaning. I'm hoping that observation just saved me $1700. bucks for a re-power that I was thinking about getting next year and won't be a two year project as I thought! I'm keeping my finger crossed! My final diagnosis with this was after I removed the flywheel, (I wanted to clean up the stator and inspect the magnets anyway) I realized the reason the bolt backed out. The lockwasher broke and fell out causing the bolt to vibrate out to the flywheel. If any of you fellows that own 620's or 720's hear a knocking noise, check the bolts in the starter motor mounting plate first. It could be your "knock". Just thought I would share....
Steve@B&B

Great to hear Steve!  You are on easy street now!