By meat I mean deer and elk. It works fine if I don't add fat.
We tired to grind some beef for a friend but the fat content in the beef was enough to also clog the grinder
This tells me that you have a few problems. Remember a grinder "cuts" so if it's not cutting look at the surfaces first.
1. Your blades could be dull. If there is any roll over on them or glazed spots you need to sharpen them or replace.
2. Your plate is warped, pitted, or worn out. If the blades don't sit flat over the whole surface then it will plug up and not cut.
3. You don't have enough pressure between the plate and the knifes. You have to tighten them up good.
If your blade is worn and can't contact the plate then you should replace both as well if your not trying to grind too big of pieces through a small plate. This is what I would do;
Get a nice flat stone and using a circular motion with a little WD-40 (works better than any oil or spit) on it flatted both sides of the plate. Next get your blade sit it flat on it and do the same until the blade has nice new metal entirely across and no dull spots or rolled metal at the tip. Next clean and reassemble paying close attention to ensure they are touching and tighten it up.
I always put some oil on my parts when I put them away as well, just a lite coat.