Hello. I bought what the guy says is a late 70s to early 80s Asplundh chipper 12 inch. Experienced friend in the industry says this is a "whisper chipper". I'm told that this is a Ford 9N engine if that helps. There is no information on the machine at all. The guy demoed the chipper and it seemed to chip fine throwing out 50 cent size shavings, but an occasional strip of wood - which he said means that the blades needed changing and sharpened. But it pulled branches in and chipped them pretty good and shot them out 20 feet. Long story short I took it home and put some re-sharpened blades in it that came with it. I'm having trouble though figuring out what is the correct way to put blades in this machine and I have switched them in and out 5 or 6 times now adjusting different stuff. When I put the blades in with the beveled side facing down/out (bevel facing out from the drum) the chipper will not pull and chip regardless of adjustments that we make to the gap and cutting bar height, etc... You pretty much can't even force a branch through. It just digs a few chips out of the end of the branch, hollowing out the end of the branch - but noticeably leaving a lengthy bottom "shard" sticking out. The guy I bought it from insists that the bevel side of the blades is supposed to face in towards the drum - and when we reversed the blades in this manner (as the seller said was correct) the machine cut reasonably well this way for about 1.5 hours and then stopped pulling and chipping again. When we went back in one blade was mostly shattered into 5 or 6 pieces and all four blades had chunks missing from the beveled edge (maybe from where the one blade broke up). Every YouTube video and diagram I have seen seems to indicate that the blades are correctly installed with the bevel down/out and away from the drum (opposite of what the seller says is correct). (1) I critically need to know which way these blades are supposed to go in. (2) It at least chips awhile when the bevel is up/in, facing the drum. Did ANY of these chippers call for that? But it shattered one blade and made the other three useless when we did that. That is the way that the seller says is correct though. 3. If the bevel is supposed to face down/out, why will it not pull the branches in and cut? We are setting the gap at about 1/32nd, but I do notice that the cutter bar does appear to have some rounded edges. But would this prevent even being able to force branches in altogether? Any help is greatly appreciated and thanks! Also does anyone know the best source for parts, knives, etc....?