Nobody is going to like the following words: I have had my auto p/t for 4 months and use it everyday. It has worked flawlessly on my computer, in my car, and it is producing clouds of 555 vapor as I am typing this very moment.
I recently got a 2nd p/t a month ago and so far it has performed flawlessly, although there is a slight difference in design on the end where the Carto screws on.
My friend has gone through 2 auto p/t in the last 60 days, 1 heated up and died while the other just died or so he thought. He contacted me about the 2nd, took a quick pic and e-mailed it to me. The newer p/ts have smaller, less-defined "terminal post/center connector" for lack of a better word and smaller center hole. This difference exists with both of my p/ts as well.
The newer terminal posts look like they are thinner in design and I have recently had to bend them up on some of my batteries which share this newer design. I suggested to my buddy to take a paper clip, place it in the center hole and apply a little leverage on one side to lift the contact and then the other to even it out.
Bingo! His once dead p/t is now alive and kicking again.
All it takes is one Carto that has center connector/terminal post whatever you want to call it, to be off by 1-1.5 mm, that is to say longer and it pushes the batt or p/t center connector/terminal post down. Go to screw on another Carto, now it doesn't work. Try a few more Cartos, still doesn't work, but put the last Carto that worked on it and it does work. (sorry kinda excessively wordy)
I'm sure this won't work as a fix for everybody, but it's at least worth a try.