I'm about halfway through my top-end rebuild, and I decided to lap my valves while they were out. I'm regretting that decision now. They weren't too bad, but there was a small amount of visible pitting and roughness. Now, I've got these grooved rings around the valve and seat, which is - if I understand correctly - THE thing to avoid when lapping valves. I'm not sure how I did such a poor job of it.... I've never done valves before, granted. But before anybody bites my head off - yes, I read up on how to do it. Thoroughly. I read the cautionary tales and watched the videos. I used a suction-cup type lapping stick and a combined pack of the course/fine lapping compound. I was conservative with my application of the compound. I started with the course, and once it stopped making noise, I wiped it off and transitioned to the fine grit. I lifted the valve, rotated them, and smacked it back into the seat to spread the compound whenever the sound started to change (or sometimes more frequently).... I cannot, for the life of me, figure out where I went astray. Anybody? And how buggered are my valve and seat?