Ok, my vapcap M arrived! A quick clean and burn-off and I gave it a good try.
Nothing...covered the carb to get more airflow and it was totally blocked, Monica Lewinsky couldn't suck anything through that.
Bit of playing around and I found there was absolutely no air getting under the cap, it was sealed tight, however I found a mention of the 'file mod'. A couple of strokes of my leatherman's file across the ends of the helix made me very slight notches like the Ti tips and I prepared to try again.
Heated it up to the click, covered the carb completely since I'd been unable to get a thing last try, and sucked as hard as I could. I'm still coughing as I type this, the filing worked to let some actual air into the tip and I know not to do that again unless it's through water maybe.