Update: We are up & running.
After much frustration, I had to cut the shaft. With the shaft cut, I was able to retrieve the coupling unit from inside the motor leg. I figured once I had the coupling unit in hand, it would be easy to knock out the remaining piece of the shaft — not so. I tried numerous chemicals and heat but it wouldn’t budge. I tied using a pin punch tapping on either side of the center pin but, no go. What finally worked was to remove the center pin from the coupling unit, placed it over an open vise, and using a 3/8" socket extension took out my frustration. Finally, little by little it started to move.
Once out, I was able to install the impeller and the new shaft (thanks to RPSIII) and we are back in business.
Thanks to all who responded and especially Bob S(aka RPSIII). I couldn’t have done it without you guys.