Bad bearing or bad bearing housing. The bearing should be a press on the shaft then a pocket in the outer cover that it sits in should only have a few thousands end play. So for that shaft to move out that far either the bearing is coming apart or that end cover is worn through. Also you might check to see if there is a little snap ring behind the bearing that would be used as a stop. If there is one it could have gotten dislodged and let the bearing slide down the shaft.