After using mine on the farm, if they gum up and not open, I just spit on the blade and rub it around, good to go again. Not amazing but works in a pinch when you're actually out working in the field, not just a hobby farm.

You want that nice close blade on jaw action, it's natural that they gum up with sap or dirt from the bark. If you really want, take out an oily rag and clean them when you need.

But it's not like something should just "work forever" without some care.