91 Accord - Sunroof doesn't fully close

I have a 91 Accord Ex. I opened the roof and when I went to close it, it did not fully finish. Very small ~1/2" distance, but you can see the back of the roof has not fully lifted. It worked fine for years, and then all of a sudden this happened...I looked for debris or other obvious things in the track, but I don't see anything. Any ideas? Thanks much!