I'm a soap bubble guy. Put a few drops of dish soap in a small glass of water and use your finger to "paint" some on around the screw you loosened. If there's a leak you will see tiny bubbles forming. I actually keep a spray bottle of soap & water in the basement with my plumbinig stuff. I used it to find a slow leak in my ATV tire last week and stick a plug in it. I use it if I am running new gas lines, too, to check my connections.
And of course all the ways YT mentioned will work, too, but soap & water will find a leak no matter how small and is very safe.
Knowing YT, he would probably want a baggie full of butane to dispose of