I've had the Apollo VTube for a few months now and it has been a wonderful device. I've been using Boge XL carts on it without any problems until recently. About two weeks ago, I noticed it was becoming harder and harder to screw the carts in. I'd have to keep it straight and apply a little extra pressure to get it in. Now, they don't screw in at all. It almost feels like the threads have stripped, but I am able to screw in a SmokTech atomizer without problems. I decided to get the 510 to Ego adapter to see if that would help (plus I've heard it makes the draw better), but although I am able to screw in the adapter without problems, the cartomizer doesn't burn when I push the button. I guess the connection isn't correct. Unfortunately I don't have a true ego Cart to try. So, I'll assume the adapter doesn't fit my carts, but I am still wondering why I am having a problem screwing in the Boge's in the first place when I have been using them without problems for the entire time I've had the device. I've tried screwing in others to see if it was just the one cart giving me a problem, and they all are not working. I even found an old cart I had thrown away that previously worked, but it too now fails. Any idea why this is happening or what I can do? I love these carts and i have about 5 packs of them to go through. Would hate to play the guessing game on new ones that might or might not screw in. Snap of what it looks like. Funny thing is, if I can get the cart to stay on when it's crooked, it burns fine. Unfortunately I can't carry it around like this because a bump will knock it off.