I've been playing with the custom settings , using the right extruder.
Still waiting for a replacement for the defective left extruder - Flashforge support said they will provide one but between them and the supplier I bought the machine from (Technology Outlet) I'm still waiting for some progress.

In the meantime - what is the recommended method for calibrating the feedstock?
It seems logical to measure the filament (in my case 1.65mm) and enter the actual size, and the use feedstock multiplier to 'tweak' it.
Coincidentally, the default setting was at 1.77 with a multiplier of .93 which calculates to virtually the same as putting in the actual of 1.66 and starting with a multiplier of 1.