Hey Robert, I think your absolutely right about the hand-held hone. Back in the day when we ran the Corsair T-72’s, we always used a hand-held hone whenever we stuck a motor. We’d fit a new piston, and most of the time it would run just fine. But every now and again we would stick that motor again and we couldn’t figure out why. Then one time at Mid-Ohio I stuck it in practice and my dad was having all kinds of trouble with his twin, so he told me to take the cylinder over to Don at LAD and have him hone it for me with his Sunnen. So I did, and as Don was measuring the cylinder the first thing he said to me was, “so you honed this last time with a hand-held right?” I asked him how he knew that, and he said the cylinder is cone shaped. The bottom of the cylinder is larger than the top of the cylinder (or vice-versa, it’s been over 30 years so I can’t remember exactly). Either way, he said that is common for hand-held hones. So he cleaned it up, we stopped using the hand-held, Dad bought a Sunnen, and we never had that problem again (that is, we never had the cone issue again, but I still blew up a few motors lol). Good luck at your next test.