If this is the engine I'm thinking it is, it has some funky shaped "synchro-balancing" gears inside that are on short shafts which are pressed into the case. I had one that these shafts had apparently been knocked loose and definitely tried to be repaired by brazing the case. The engine ran good enough for me to buy the 950 it was in for 400 bucks. I got it home and after cleaning it up I fired the machine up to test drive it... it ran great for about 30 seconds then started shaking violently and before I could shut it down, locked up. When I opened it up was when I discovered the shafts had loosened up and the gears were jammed, the engine was toast. Needless to say, the "reputable" big time duck hunter who sold it to me refused to give my money back. And yes I DID expect him to since he had owned it for some years and had sold it to me to be in good running order. Especially after the guy who had originally told me about the machine informed me the seller was the one who had the repair done... funny, that was never mentioned before I bought it...buyer beware! They are good engines and stout, I was just unfortunate to have gotten one with some problems. Hope yours is as good as it has the potential to be.
DESTRUCTION is just a couple of vowels down the street from DISTRACTION