Mine has the same top number. So the bottom would be serial or like you said batch. Most likely all samples have a 1, but it would be way cool if it meant 1st one. And I hijacked ur pic I been using 4id as well. No pics and I was going to wick it this am but no time. I keep the CB thick when threading it because I want enough tail to work @ where the cotton makes the turn. Once threaded I move it back and forth to loosen what's making contact with coil. A bit looser than some other builds whilst still having contact. Some dry hitting could be from having it too tight in the coil. Then I fluff and fashion the tails so after juiced I know it won't be compressed by the chimney or in the wicking channels. I did a little measuring and after screwing down the chimney, there's right about 2mm of space between top of deck where wick is and top of chimney cap, however, I go with the top of the deck as my guide to be flush > after juiced. I wanted it to be fluffy after juiced. I initially checked using the broad flat end of tweezers, to see that it didn't press it in. I also gave it a thin little down the channel to about the bottom of the screw,< Result for channel is like less than half the depth is cotton, and after juice > zero chance of compression or touching threading. So I'm mindful of that when the cotton is dry. Juiced and using the tweezers, I "gauged" it the first time. I burp it when filling. 35+ ml of juice and I get a couple minor specs under the tank about every 2-3 fills. So not spotless. Nothing called leaking or seeping tho. No dry or anemic hits. Just full on flavor.