The high-pressure water blasting made no difference in clearing the blockage(s). The plumber was kind enough to charge us only for his time, and not for the use of the pressure-blasting equipment.
Current plan now is to dig a hole (either through the basement floor, or outside in the yard) down to the main to add a clearout. That way the auger can skip the three turns and go directly into the straight section.
We will be asking plumbers for bids later. For now, I am focusing on the floors.
