I have the same problem with my driver's side visor drooping. I tried cuttng a small piece of velcro and attaching it to the rubber molding of my sunroof and the inside of the visor. It did not work too well. It was fine for holding up the visor, but when I went to pull it down, the velcro adhesive was not strong enough to stick to the the visor fabric and would pull off.
If you do not have a sunroof, I do not know if the roof fabric will provide a strong enough bond for both surfaces.
Stone
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"If you can dodge a wrench, you can dodge a ball."