I just answered my own questions after cogitating on it with you Uncle
If my cartos did not leak with my home made tanks but did with the purchased one, it had to be the tank. The only source of air was the little plug. I covered it with my thumb and tried to suck air out of the tank. I had a good vacuum. With the plug in I could not form a vacuum. So I cut up one of the little "condoms" that come on the cartos, cut a very small hole in the center and used it as a washer around the plug screw. Now I had a vacuum. I slotted a new carto, put it in the tank, filled it 1/2 full and replaced the plug along with the washer and No flooding, no leaks.
Evidently the hole is too big or the plug is too small, but with a little washer it seals fine. Problem solved
Between you, awsum, Kon we have all the vaping problems covered
Hi Uncle. Nice to see you.