Putting it on the head of the screw won't prevent it from coming out, when it's the THREADS of the screw that are loosening. Also, Loctite can eat the finish if any of it comes in contact with your guitar. Instead, go to your local CVS/Walgreens?beauty supply and buy a small bottle of Sally Hansen's "Hard as Nails." It won't eat the finish of the guitar, it's clear and it works. Use the enclosed brush, and put it on the threads of the screw that go into the saddle. You don't need much. You have about 2 minutes to line up the saddle and re-intonate before it hardens. I've used it on eyeglass frame screws for the last thirty or so years. If you ever want to remove it, just back the screw out, and put a little nail polish remover on the screw threads. And Bob's your uncle.