My 80-051 has snapped in half, was it from the door weight?

Yes, looking at the photo I can see the stationary door seems to out at the top. Check the bottom track under the doors. It could be that they have settled in the middle. That would cause the stationary door to pull out at the top. I would suggest to shim up under the complete track and check it with a level to make sure it is straight. The sagging track could also effect your sliding door. Loosed up the screws at the bottom track (you might need to get the stationary door out of the way), install some shims caulk and reinstall the screws. Make sure you caulk any holes or seams to keep water from getting underneath the track.