sun visor problem

[lakeside]

I fixed the floppy sun visors at the ball end following instructions on this forum. That part works like a charm but now my problem is that the visors are not tight on the horizontal arm that passes through them. The adjustment screws don't tighten with enough friction to keep the visors from falling to the down position. I'm thinking of pulling the visors off the arm, if I can, to see if I can somehow, add some friction to the bar, and, hopefully get the visor back on the bar. Can the visor be pulled completely off the arm and replaced? Also, I'm thinking of drilling through to the back of the visor and placing a screw and nut through the visor to draw the visor tight against the bar. It would look like crap but might work. Has anybody done this? Advice?