Parker Duofold Centennial

I bought this pen not because I wanted it but because it was there. Now what to do with it?

M sent me his wider 18k nib to test and compare to the original 14k two toned nib that came with the pen.

I tested and retested on and off all evening yesterday until I was confused by the line variations, the colour in the pen and my reactions.

Then today, it seems that both nibs are skipping.