Don't recall where I got my first one, it was really tight and had to be on a device in order to give something to hold onto to get it apart. I just ordered 2 more from myvaporstore, so I hope they're as tight as the first one (that I dropped and broke the ground leg on last Saturday while wrapping a coil - Argh!) If it's loose, you can probably tighten it up with thicker o-rings or put a couple wraps of plumbers tape under the o-rings to make them engage better. Probably only need a couple thousandths to get a good grip.
Thanks bro!