When I bought my rex the sunroof was doing much the same thing as yours. It would go all the way forward, and even go down from the tilt position, but NOT all the way, so there was much wind noise and it looked funny from the outside. This is what I did to fix it...
My advice is to remove the sunroof panel and get a better look at what the moving tracks are doing. Pop the two bolts out from the front of the sunroof. Also I believe there are two plastic pieces that are screwed onto the back in line with the track. Then slide the panel back and up to remove.
Operate the sunroof switch and see if the tracks are out of time a little bit. That is what happens to mine sometimes. I just hold one of the tracks back with a large screwdriver while the opposite one moves. You don't want to try and stop it completely, just slow it down. Do this back and forth, periodically operating the tracks all the way closed, and see if the arms that tilt the sunroof up go all the way down.
Usually one track will go all the way forward and the opposite side "wing" (that tilts the sunroof) goes all the way down. The opposite TRACK is just shy of moving all the way forward, so the corresponding wing (that would be on the opposite side) stays up. The pass. side track is tied to the drivers side wing, and vice versa. You need to get both tracks all the way forward so both wings go down.
I use the trusty big flatblade screwdriver again to push forward on the track that is not all the way forward and "persuade" it to move farther and drop the opposite wing down. It helps to have a friend, one on switch duty, the other with the screwdriver. Monkey with it and curse at it enough and it should close. My sunroof completely gets out of time if I open it past about 60%, so I have done this a few times with the same good (closed roof) results.
Good luck! :wink: