The RAS is a Rockwell / Delta catalog # 33-890 12" S/N 85H05429.
The crank got hard-to-turn about 6 months-ago. I lubed every surface that was accessible with little improvement. It became altogether in-operable 5 days-ago ... the crank turned ... looking at the gears underneath ... the gears and the vertical shaft were turning, but the column wasn't moving. Looking at the parts explosion ... it seems that the first item installed to start the assembly was likely installing the raising nut at the base of the raising column.

I'd appreciate some 'coaching' from anyone that has done this replacement as it seems to me to be a total dis-assembly.