I just joined this forum to find out the same thing you are asking. I went through 2 JoyETech E-Vics. This is a great unit, problem is it doesn't last long, at least for me both units had issues with the control head. The first one I am not entirely sure what the problem was, however on the 2nd head the problem was the dome that is right about the screen. That part of the evic is made of two parts, which was news to me until today. The dome is actually the female piece, and the male piece is the part that is glued to the black plastic where the screen is.
The problem is the glue, it sux, no other way to put it. The unit will turn when you are screwing the cartomizer off the top of the unit. The unit will also come undone if you happen to put the evic in your pocket. I noticed the turning one night while I was removing the cartomizer to fill it. The top of the unit, the male and female literally came off the black plastic. I could see the wires underneath. I went ahead and used a special glue that I use for my business that is designed to glue aluminum to aluminum and aluminum to plastic, etc. Once glued, problem solved. I am not sure if this was the issue with my first eVic, however it was the issue with the 2nd one.
Today the actuation switch quit. Didn't matter how many times i pressed it, it just stopped working. I am not going to buy another control head to replace, too costly, and after 2 strikes, no more for me. I went to the local vape store and purchased a telescopic unit made by a company Smok. I purchased this particular unit because I wanted to use the batteries I have here for the eVic, and I also did not want the frills that the eVic provides. I use the unit to save $$$ on cigars, I never inhaled cigars, and the cigar flavors that are available are excellent, so these days I only smoke a real cigar when I go to the local cigar bar/watering hole, LOL. Needless to say I have saved big bucks with vaping. I use the zero nicotine, as I never inhaled cigars only puffed on them for the flavor. My wife is also elated with the vape choice.
So far after a few hours the Smok Telescopic works fine. You can't adjust the voltage, but it has a nice output. I am using the Kanger MT3 Tubes, which have worked best for me. I purchase the Churchill liquid from Liberty Flight, that is an awesome cigar flavor and it does the trick for me.
I hope you find this helpful. You may want to check your control head and see if that is the issue. I am sure that problems will arise if the wires under there pull and come disconnected while you are replacing the cartomizer. Definitely something to look at. Hope this helps.
