I just changed the teeth on my 252. My first time changing them and third time using the machine. What a difference! The teeth that came with the machine were very dull with no edge at all. I had a friend of mine who works in a machine shop sharpen one of the old ones. He did a good job putting an edge on, but a lot of the carbide was lost because he had to take so much off to get the angle with a good edge. Is there still a lot of life still in them? Will they work good or should I scrap them and buy a new spare set?