I'm rather stumped by the fact that some of your descriptions have sounded like your unit is running cool, and others too hot. You mention weak hits one day, then combustion the next.
Not to mention if your unit is running hot enough to combust material, milking a bubbler should be no problem.
Strange thought, but are you always using the unit in the same room, same outlet? Are do you move it around and plug it in in different places?
Is it possible the the wiring in your home is a bit wonky? Have you ever used a multimeter to check your outlets voltage?
So some of the descriptions may have sounded like the unit is running cool, but i've also made it clear that from what I can tell, the unit is not running cool. I am pretty sure that's not a possibility. I meantion weak hits everyday, just to be clear. The one consistent thing is that the hits are not satisfying. Combustion is not the goal here, it is undesireable in this case.
This is why I am so baffled by this unit. From what I can tell, it is not running cool, it actually gets very hot when I have it plugged in for over an hour. Initially, i assumed i needed to dry my bud out, but that did not have any noticeable difference.I have tried 3 different strains with this unit.
I figured I would just use the unit with my glass and not straight draw from it. The real frustration came when my glass arrived. The unit barely milks. After taking a zillion hits, it just seems to me that the loading of the stem and the actual size of the stem are the problem areas. First, to load the stem you need to put in a very small amount, if you put in too much, when inserting the stem into the heating unit, the heating unit condenses your bud into a small ball and it strangles your hit. If you do load the proper amount, in my opinion, it is not a sufficient amount to get a nice milky glass hit. For me at this point its very hit or miss.
Have only used the unit on one outlet.