With the TM, the uneven looking ABV is a fact of life. FWIW, I never felt that I was getting "less" out of my flower, and personally it seems mostly like a cosmetic issue (if I'm getting the right amount of effect from a given amount of flower, I don't really care what the ABV looks like).I had tried everything I could find to do with my first one, including the tin foil shim and the wiggle and tighten. I would think the chances are slim that 2 out of 2 devices would not be working properly. Especially since they do function and seem to both function very similarly. I mean it does vaporize the product with enough sucking and stirring. I definitely get smaller hits than with my Dynavap or even my Mighty but with added throat irritation and uneven extraction. I have tried the basket screen mod listed in these forum it doesn't seem to improve anything, just makes it so I can use my upline stem.
Maybe its just the difference of pure convection and I don't like that? This is my only pure convection device.
Seems like you've tried lots of things and even gotten a replacement, so it's hard to say what the issue might be, but I will say small hits doesn't seem to be a complaint with a properly functioning device.