Hello,
Your wood chips should never be 4-5 inches. They should be 1-2" size chips. You have some issues as I think your knives are dull. Another issue is that it sounds like the anvil/cutter bar is too far from your knives. From time to time, a branch will go through the machine and it won't chip.. That happens on all chippers. Anvils usually can be flipped as they have 4 edges. The edges should be square. If not, a used edge will look like a rounded off table edge. This creates a larger gap between the knife and anvil which in turn creates a larger wood chip. The distance between the knife and the anvil should be a about a 1/16" gap. When checking for the gap, you should always turn the drum backwards as not to damage the knife or anvil if they were to hit. When you think the gap is correct, then turn the drum by hand in the chipping direction and check the clearance on all of the knives. Please remember to remove the ignition key prior to performing this repair.
The Woodchuck Corporation sold out to Altec many years ago. Altec is no longer supporting Woodchuck chippers that are older than 20 years. Our company can help with bearings, belts, knives, anvils, and clutches if you ever need them. Other parts may need to be machined by a machine shop which can get costly. A WC-12 is a very old machine and the numbers you provided will not help in identifying the year. I've been doing this for many years and I'll about bet you have an old Ford 300 engine in the chipper. It might be a diesel. If you have the engine serial number, you can call the maker with the engine serial number and they should be able to tell you the year.
Hope this helps!
Dave
Global Equipment Exporters
770-420-6400
