Hello! The woodchuck chippers work great but everything must be adjusted properly for them to do so. Knives must be sharp and i mean sharp. How many hours would you say are on those knives? You should also see that there is what they call a bed knife that should rise above the feed table about 1/8 of an inch, There are adjuster bolts under this raise and lower it. The knives themselves have to be adjusted so that they are extremely close to the bed knife,about 1/16 of an inch. This job can be really difficult without the right tools and gauges to set and measure limits. Not saying it cant be done. But working for a dealer who also services the woodchuck chippers I have set many of them and couldn`t imagine trying to do it without proper tools. Also note that by setting them improperly it will never pull in the wood and improper adjustments could cause the knives to crash into the bed knife causing lots of damage.