Old nikon camera is broken

Not sure the exact model. I don't really know much of anything aboot cameras but its not the digital kind. 35mm i think? Anyways, it's pretty old (80's?) and i really like it.about three years ago i took a picture just like i normally would, except i couldnt see through the viewfinder thing after i released the button. So it just sat on my shelf for three years, until today i took it off the shelf and took off the lens and unscrewed a few things to see if i could find out what was wrong with it. I found that the mechanism inside that moves the little mirror won't automatically go back down, to the position where you can see out. If i take it apart i can manually push the little arm and make it sort of snap back into place, where it then functions correctly until i release the button. If someone who knows about cameras knows anything about what could be wrong, how i could fix it, or how much it would cost to GET fixed if it's something i can't do myself, i'd really appreciate it. I wouldn't mind taking it in to get looked at but i'm the kind fo person that likes to do things myself wherever possible. Also i'm pretty much totally broke, so free is kind of the only option.

but anyways, wow sorry for the rambling…

Bring it to a film camera technician. You can get a better idea from him.