If the rod & tube are both metal, tinning a layer of solder on the rod would work, but is labour intensive. A slight bend in the rod might be enough to do it, or a few strikes with a chisel on an anvil. I suspect the factory might chose the latter as a quick fix.
Mole grips might persuade the tube into a less than round shape, but protect the visor with a neoprene shield at the very least.
If the rod is soft metal, molegrips might just squeeze it out of round enough to grip.
