or any other gripper, for that matter. after 200 or so rackets, i noticed that the gripper of my wise is not smooth anymore. the two plates that grips the string doesn't always bounce back to the normal position after it releases the string. or in some cases, it doesn't even release the string. so off i went with the allen key and carefully took out the gripper body and proceed to clean the whole thing. taking of the body requires taking out 4 bolts that holds the outside plates together. becareful not to let go as the bearing inside will drop and create a big mess. after having the whole assembly off and the parts sitting on the table, it was obvious what is the problem, over time a lot of powdery stuff accumulated at the needle bearing as well as the plate themselves. probably the result of string coating shaving off during the process. out comes the degreaser and the whole thing was spotless after 10 mins of cleaning. i used some napkin paper to make sure that everything gets a clean job. other cloth can be used also as long as it doesn't shread a lot of fiber. after putting back the whole thing, carefully to make sure that the bearing won't drop off in the process, the gripper now feels like new. after every release with a crisp "click" it retracts back to its resting position. not sticky anymore i was debating whether i should put some oil on the bearings. i might just put a couple drop just to be sure. otherwise it is working very smoothly now. i clean it on my WISE but i am sure similar procedure will benefit other machines too. so if you find your gripper getting sticky and not functioning as smooth as it was new anymore, try cleaning it.