If you will post the make and model it would help.

The make and model would help. It may well be possible to remove and sharpen the existing blade(s).

Probably needs sharpening. If sticks have mud on them, will take the edge right off the blades.

I keep a pruning lopper and chainsaw nearby when shredding. Anything with mud gets cut off.

I just sharpened mine. It takes me about 30 seconds to chip a dry 11/2" cherry branch. Plus it shook the hell out of my arm while pushing it in. I had to use an acetylene torch to get the screws out of the blade. I used the side of a spinning grindstone with no table to keep the angle right free handing it. That's just me! Yes I wont be putting any dirty stuff threw the chipper either! Mine is a 1975 five hp Mackissick. New to me though.