09 dragon 800 rear shock and drivetrain messed up

my buddy has a 2009 dragon 800 that somehow broke the rear shock off while just riding down the trail. I have heard of some other ones doing that. What causes them to shear the shock off and bend the shock arm at a 90 degree angle? ALSO, the track sounds like something is hanging up. It makes loud thumping noises when going anywhere from 0-60 but over 60 it smooths out. Going in reverse for more than 5 feet will bind up the track and it wont move. Any thoughts? Rolled it on its side to turn the track but cannot find anything hanging up

Anyone had this problem?

Track is tight. Didn't scissor down because of front shock in there