So the followup...
Tech comes today. Removes pump, determines that pump is still operational. He then determines that the pressure regulator on the water line has become clogged with debris from when some newbie drained the lines

.
Clears pipe and regulator and lights furnace, furnace works properly. $75.
Roughly 45 minutes after I had left for work and Rosie was preparing to leave a noise is heard and she goes down stairs to check and steaming hot water is exiting the relief pipe. Had this happened later while we were both gone

. Water was everywhere in just a few minutes.
Guy comes back, replaces pressure regulator. $125.
So in all, $75 for the first check, $75 for the supposed fix and $125 for the second fix. $275 is a whole heckuva lot better than $500.
Happy to have heat, but not about the price. The good thing is, I happened to get a nice little bonus the Friday before the boiler went kaput and I thought it was going to take a big chunk out of it. But it only took a little nibble <S>.