ldquo See that rdquo The clock repairman pointed his flashlight beam on a small fine mark roughly engraved inside the old grandfather clock he was working on in our home ldquo Another repairman could have put that there almost a century ago rdquo he said ldquo It rsquo s called a lsquo witness mark rsquo and it helps me know how to set the mechanism rdquo Before the age of technical bulletins and repair manuals ldquo witness marks rdquo were used to help the person making a future repair to align moving parts with precision They were more than just [... more]