1) Anything radio shack brand isn't worth its weight in dog shit.
2) My variable power supply rarely gets used when I'm using actual herb. I find that I've never had green left in the stem like you describe with your zap. Never never.
3) Somehow when using my aqua vape my ABV comes out much darker than when I use a regular stem or glass stem. Based on this I believe that with the underdog if you take a long continuous draw it'll cook even darker. That is the only thing I can think of that explains why the aqua vape results in darker abv. I definitely take longer faster draws when I have water filtration.
4) With the underdog it is actually easy to adjust how spent your ABV will be with a standard or glass stem. Just make the bowl smaller and bring the screen closer to the end of the stem. This locates the bud closer to heat it darker, or push it in more to have some left if you wanted a light cooking.
Dave, I lost my tracking number slip. It was in my car which went in for service. I looked everywhere :/ Sorry I can't give you more info on that. I have no doubts it'll get to you though. I have faith in UPS. Its the USPS and Fedex around here that have me scratching my head wondering how they stay in business.