Many thanks for all the insight that you have offered. I particularly like the very simple solution offered by Derek - that is remove the worm assembly to give access to the worm-gear for cleaning. But I opted for an even simpler solution. I recalled that the gears stalled while going to first alignment star in the east. So in daylight with no telescope or counterweight/shaft installed, I chose an alignment star?west of the meridian, in this case Vega. It began slewing to that position without stalling. That exposed the portion of the worm-gear (AKA ring-gear) that had the grit in grease, causing the problem. Then I used a plastic tooth pick and a toothbrush to clean the offending material off the gear. After that it was able to slew to alignment stars on both sides of the meridian. It even did a decent job of pointing at the Moon, which was visible in the afternoon sky, high in the southeast. So problem solved.
Best Regards to All,
Russ
Russell Milton