I have both the DB and GP prop balancers and find them both very good. The smaller props I balance on the GP aren't off at all when I tested them against the DB. I haven't a clue why others have a problem but I have had my GP for about 20 years so maybe there is a difference in the newer ones? Other then a bent shaft or loose fit into the prop what can go wrong?? My smaller props are all APC and the GP balancer can handle up to a 15 or 16 inch prop. I'm not a huge fan of Great Planes products but the balancer has worked out fine.