(1) Hooked hand: pay attention to the frequent replacement of the elastic rubber part, if the finger hook is broken, skewed and the rotating shaft is loose, it should be replaced or repaired as soon as possible. (2) cable-controlled dummy hand: when the control cable is bad, you should find out the reason, whether it is an internal structural failure or control system problems. (2) control rope system (1) the friction between the rope sleeve and steel wire will often appear oil, control rope jacket after the plastic tube, the locator part of the oil produced will still dirty clothes, it is advisable to replace the parts as soon as possible. (2) When the control cable is not flexible, oil or lubricant can be injected into the cable sheath, but the action status of the control cable strap and the dummy part should be checked first, and a small amount of lubricant should be injected after finding out the reason of inflexibility. (3) Loosening of steel cable joints and cable ring connections, often caused by poor welding or riveting. After clarifying the cause of the failure, decide to replace the parts or repair. (4) The backstrap part is easily soiled by sweat, and malfunctions can occur due to rust in the part of the backstrap (leather, belt) and metal connecting parts. Use rust-resistant materials to make the loop and strap cord.