problem with 1989 BMW 520i aircond sliders. HELP!!

[thehaz]

hi..

i own the above mentioned car. the problem started yesterday. u know the slider which toggles the aircond to either be blowing forward towards your body and there's one for blowing towards the feet..? well yesterday when i was adjusting the sliders, the middle one (blow towards the body), couldn't slide all the way to the right. instead when i push it there, it'll bounce back to the left as if there's a spring that's just not catching properly. and now.. i can't get the main aircond vents to blow any air out of it. but i do feel some cold air coming from below towards my feet. i'm not sure what's the problem here. i can hear the aircond working, i feel it at my feet but not from the main vents. how do i fix this? why is the slider bouncing back to the left? can i DIY the fix myself?

thanks.