Checkout out the thickness of my blades! One interesting point is the bottom roller, which sits between a pair of removable guides, which should help the thing self-feed without jamming.

then inspect the hopper and blades and remove any objects stuck there. The obstruction clearance methods may vary between different wood chippers, so follow the instructions in the manual.

Depending on the conditions that your wood chipper is used, a rule of thumb is that blades should be sharpened every 25 to 50 ...