Well, about 2 weeks later and lots of consternation, questions, half
baked theories, and speculation by contractors, city sewer department
workers, and neighborhood kibitzers, to say nothing of my friens at
alt.home.repair, here is the verdict.

Right after the sewer line was supposed to have been cleared, it was
backed up again. I decided to ditch my plumber and I called in Mr.
Rooter, a local franchise of a national? company that offers free TV
inspection. I watched the video imagery and saw the camera go through
a sea of sewage (just before lunch). But the truth is you can't
really see all that much if the sewer is backed up. They said they'd
jet it out so we could see more.
The hose got stuck, and they thought because of a break in the line
just outside the house. They said they would have dig, and an hour
later they had a back hoe out front and were digging, about 7 feet
down. What we found was not a break but a huge gap in the line, about
2 feet of pipe so rotted there was nothing, not even shards to be
found. What I had was a cess pool outside the house. The rain from
the roof had been pouring down into this corner of the house and
seeping back into the basement through the sewer line, which was full
of sand and sludge. They found all the cast iron pipe going into the
house was also corroded beyond hope.

What they are doing is a "trenchless" sewer line replacement where
they fill a liner with resin and force it through the line by air. It
is quite a system and will avoid having to dig up the entire front
yard. It comes with a 50 year guarantee and at 61, I can accept that.
The missing or corroded parts they will have to replace, and I don't
know the details there, but it will also be lined with the new resin
material.

They showed me how it worked and told me it was invented in Europe
where there is lots of old pipe.

Bottom line: it will cost me $6k. As my wife noted, there is no
choice. I'm spending much more than that on a marble balcony and
veranda on the back side of the house, which is going on
simultaneously. I will enjoy them much more than the new sewer line,
but in the scheme of things my money on the sewer is probably better
spent.

Thanks for all your advice and interest in this matter.

--Don