Flavor wick is killing it man. Not needed with rayon at all. Rayon will last you at least 4 times longer than cotton if you get the density right and ditch the flavor wicks. I do have one running for my wife - it just keeps going and going.
Look at the diameter and height of the coil too - if it's the same width as the juice channels, and lined up with the bottom edge of the juice channels (both optimal IMO), then you'd automatically get the right size rayon puff without needing the flavor wick, it would be at the perfect height, and everything would be beautiful. But if you're wrapping them narrower than the juice channels and/or setting the coil too low into the deck, then the sucker would leak and flood all over the place, and performance would be lackluster. I was getting 4 times longer too, compared to yarn.
When I first started rebuilding Kanger heads, I looked around the house for something that would fit perfectly in those channels. Ended up with one of these for my mandrel:
I think it's about 1/16"D.
When I position my coil, I leave the coil on the mandrel, straddle the mandrel over the juice channels, lightly tug at the legs, and I don't remove the mandrel until I've got the legs all tightened up and trimmed. Then I carefully slide out my mandrel, give it a test fire, and thread my wick through. No flavor wicks needed, because the puffy ends perfectly block the channels without being too loose or too tight.
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