Thought I would add my 2 cents, I had the same problems as everyone else... I have an Infinite clone of the black stingray
I dissassembled the switch and took the dremmel with a small polishing wheel and buffed the switch post and inside of the
threaded ring to a high polish.
Part 2 - clones are not machined as precise as the authentic...so if you can wiggle the switch side to side when assembled , there is too much space. The authentic is so close there is no switch wobble.
I searched for a slightly thicker rice pin to make the gap a little smaller, ended up with a copper finish nail from Home Depot that worked out well, I mounted the nail in a drill and used sandpaper to grind it down to the perfect size.
I finished it off by adding a touch of graphite power to the switch post and reassembling everything... Works fantastic!
I had a problem with certain Atomizers not firing as well, that was a much easier fix!
If you look at the top cap... See if the black ring holding the floating pin is seated all the way. I found that mine was kind of cocked and not inserted all the way.
I used a nut driver bit that only touched the black insulator part and on a flat surface gave it a tap with a hammer... And voila the insulator sank into the topcap another mm or so and now everything works nicely and the switch screws in a touch more.