Split the joint from the hub, and check for any slackness in the joint or end float (up and down movement) if the joint does not feel smooth or there is any slack or knocking REPLACE THE JOINT, DO NOT DRIVE THE CAR, if there is any slack in th joint it means that the top of the cradle (The joint housing) is wearing away on the insde, the cap will be thinner and could fail at any time letting the rod pop out of the top, losing all connection with the bottom of the hub