Craftsman mower valves?

Darn William B is a small engine tech today..He is usually a building maintence foreman..but I have seen him be alot of things depending on the question..when You broke the first valve and it was replaced, the valve seat itself was damaged from the first broken valve..simply inserting another valve will work for awhile, but now that the valve seat has been damaged..(which does not necessarily mean it will be visible to the eye) the new valves are going up and down and improperly seating...Most shops do not own valve seat grinders now days, and alot of them don't even do it..they simply tell you that you need a new mower..or throw a part in to make it temporarily work long enough to "get the money and run"..I am 54 and years ago I took a small engine repair course which we were taught to grind the valve seats when there was valve damage..they dont hardly do this now days..they make a tool for it that fits on a drill..all the way to high tech ones that have guages and meters and wont allow you to overgrind them..they need "miched" out..I am a 37 year experienced painter but I have done other things in my life..Small engines were a small part of them..