sunroof will not close completely

hello, I just bought my first maxima (1996 se). The private seller that I bought it from told me not to use the sunroof becuase it would not close. so of course the first thing I try to do is fix the sunroof. This is before I read some post on the internet about the railing malfunctioning. It opens fine but wont close, so I have to manually close it with my hand. the problem with this is that when I tried to close it, it will only close at a slight slant that makes the back of the sunroof about half an inch below where it should be. I need to atleast get it closed correctly before it rains again here and leaks into my car. Thank you for any help you can give me.