how did the snap ring pop off? did someone mess with the turbo before? replaced cover / bad snap ring install?

 

i put a anti surge cover on it and triple checked to make sure the ring was seated so im not sure how or under what conditions the ring popped off since i wasnt behind the wheel when it happened. Im sending cover and all to fp to make sure this time around everything is good to go, cant afford to have my car down again any time soon.