Got this great tip from Larry KG4ZAR:
Every ham seems to have a HT or two in their shack and sooner or later they find the rubber duck antenna loose.
Most times it’s the locking ring/nut on the chassis mount that’s worked loose. If you use one of the improved 1/4 wave aftermarket antennas, this becomes a more frequent problem.
Trying to tighten up this ring (especially on one of the Chinese radios) usually means grabbing a pair of needle nose pliers and making a mess of things, along with pinching your fingers when the pliers slip off the ring.
A much simpler way to tighten these rings is to purchase a cheap set of “snap ring pliers.” A set of these pliers (with various interchangeable tips) are under $10 at Harbor Freight and you’ll find many other uses once you own a set.