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I think there are metal crush sleeves in that visor. You can close them a bit with a bench vise. Just do it in small amounts so you can get that visor on without crushing them too much. Can't undo it if you go too far.
I just fixed the opposite problem with my '73. Mine were too tight. When I finally got the rods out, it felt like there were two tubes for each rod, a long one the rod first is inserted into, a small gap and then a short tube about 1.5" or so. The two tubes were offset and putting the rod in a bind. I moved the short tube with my hands to be more inline with the long tube, lubed the tubes with silicone lube and mine now work fine.
DB suggested they were a crush sleeve. Might be but I was able to loosen mine by moving the two tubes more inline. You might be able to tighten yours by offsetting the short tube more - that is assuming yours are like mine. If you go the crush-it route, do like DB says and don't go too far.