So now it seems to be just fine. Last night I fired it up and it still had the problem. Then I took it out and poked around in the circuitry looking for anything suspicious, jiggling stuff around some more, and pondering how to measure some of the resistors.
Then I put it back in to make some measurements, and the trace was nearly the right width. I also learned that the "SWP CAL" pot has nothing to do with setting the width, only the actual sweep ramp velocity. I initially assumed it was a gain control, but no. The specs just say that the width should be at least 10.2 divisions, so that must be the minimum that it gets to considering tolerances and drift - there's no 1X gain adjustment or comparator setting. So the trace was just about 10 divs wide, and stayed good for quite some time. I could adjust the sweep cal and set it right on to match the calibrator signal, so close enough to call it done.
This morning I fired it up again, and the width was about 10.5 divs when cold, then warmed up to where it is now 10.2 divs and holding. So, it's a mystery exactly what caused it, but I think the combination of poking around in there, working the controls more, and running time has restored it to normal. So, I'll have to call this one a done deal - I'm sure it will be just fine until I need to use it.
Ed
