[Mr.Fixit]

A cam lobe can go away in a very short period of time. If the lifter does not rotate in it's bore, that lifter and lobe will be wasted in no time flat. You are referring to a worn rocker arm however. There are a couple of things that can cause a rocker to wear, a worn cam lobe is not a cause for rocker arm wear. Incorrect geometry at the rocker, too much lift for the factory rockers will cause biding which will bend pushrods and/or chew up the pushrod cup in the rocker. That's why they sell "long slot" rockers. Misaligned guideplates can cause all sorts of problems. ANyway, I think your problem has nothing to do with the cam, I would be looking at the rocker in question and the valve stem tip. Replace rocker, see what happens.