The Haecksler H4 is a very good woodchipper, however, the H4 model has an extra bar on top of the hopper, and this bar forms a V shape where branches get stuck.

This part fits into this V-shape, and prevents this. It can be mounted without tools.

I printed it with ASA and extra thick walls and bottem layer for more strength. But you could try PLA.

The part in the photo is printed in 0.08 extra fine, but that was just because I wanted to see what my printer is capable of. 0.20 should be fine.