Can you explain how the tape should be applied? Do I wrap the whole knob in the tape?

It's actually made for plumbing joints (you can buy it at any hardware store ). It's a very thin plastic sort of tape. You pull it tight when you apply it and it stretches and sits down in the threads. It should work for what you want but it might take some experimentation to get it right. You need enough wraps to make the threads tighter but not so much that they won't move at all. I'd suggest marking the general area where your snares have the amount of tension you want and then backing the tension off and applying a couple of wraps of the tape in that area of the threads that is engaged in the nut at that point. Pull it back up to tension and see what happens. A certain amount of trial and error will probably be necessary but you should be able to find just the right number of layers of tape to make it hold. At worst if it doesn't work you're just out a couple of bucks for the tape (and you'll need to clean it off the threads).

Here's a video about this stuff...

[ame="https://www.youtube.com/watch?v=uc6BOAF2M1E"]How to use teflon tape - YouTube[/ame]

Good luck...