My first protank base popped off this weekend. I ordered 5 replacements from myvaporstore. They haven't arrived yet.
I hadn't dropped mine, but I did notice it was sitting crooked on my vamo. I applied a little pressure, trying to get it straight, and pop! I was worried that it was the threads of the vamo that were crooked, but when I put my backup protank on, it was fine.
I hope the MVS bases are good. That was the cheapest price I found. Figured if they were bad I'd just order more from elsewhere later, or upgrade to the new protank.