That would have been awesome is it worked, but alas, it did not.
WAIT!!! Scratch that. I followed this procedure and it failed with the same error, but I rebooted and eCart was no longer listed, and the install went smoothly.
What I am not sure of is whether a reboot would have made a difference before this procedure or if this procedure + reboot made the difference. In hind sight, I do not know if I rebooted in my earlier attempts.
Either way, I'm happy and will remember this procedure should it prove necessary in the future.