I had the same problem and just ended up ordering the repair kit from Mid America it includes the bushings, support elbow, and the retainer and tension spring. It fixed the problem and was easy to install. The kit cost me $24.99 but they also sell each individual piece. It is probably just either the bushing or tension spring that is worn out. Hope this helps...
I ordered the bushing for mine too and it made no difference!
What I did is inserted a small piece of sandpaper inside the plastic bushing and carefully pushed everything into place.
Visor stays up. Just be careful and patient re-installing it!
Had same problem with mine even after install of new bushings. Get a roll of white teflon tape thats used for pipe threads. You can get this at any hardware store. After installing bushing on visor, wrap several layers around the bushing itself before installing into holder. If its not enough remove and add more. Visor stays in and holds any poistion. Worked great for me.