OK, first off I want to say thanks to you all for taking the time to help me get to the bottom of this....despite my quips about the hammer, I AM going to get to the bottom of this issue, and I really appreciate all your interest and input.
I'll continue with my ink and paper experiments, and if those fail I'll send it off to be looked at by an expert...
So, tonight's experiments:
i) A thorough flush to get rid of every last drop of Diamine Sherwood Green.
ii) Filled with Waterman Black
iii) Started a new A4 Rhodia dot grid notebook (very smooth writing surface).
iv) DIDN'T use a protective sheet between my hand and the paper
v) Wrote three full close-written sheets (6 pages) - about 1500 words in total.
Verdict: No issues at all. Not a single skip. It wrote like a dream.
Past experience tells me that the pen skips badly with Aurora Black...and Visconti Black....but tonight's experiment suggests it's OK with Waterman black.
My next step is to leave it overnight and see if it continues to behave tomorrow with the same ink and the same paper.
This may seem over-pessimistic, but last night it was writing perfectly with the diluted Sherwood Green, but today - on the same paper as I used last night - it skipped badly from the first stroke. Yet it still had plenty of ink.
IF it passes the overnight test and still writes perfectly on the Rhodia paper with Waterman Black ink, what would that suggest?
Would it suggest it is a air/flow/feed issue and that I just need to be a bit choosier about the inks and paper I use?
Or would it suggest that it's all of the above AND potential nib misalignment and/or baby's bottom?
But I'm getting ahead of myself...I need to see how it behaves in the morning before I even begin to start drawing conclusions....