Use locktite on any screw or setscrew that screws into a metal part. Example: setscrews on the mast collar, setscrews through the tail hub to the tailshaft, and the screws through the head that go into the aluminum seesaw arm. Also the screws that hold the motor to the motor mount as well as the screws trhough the frame into to motor mount. There are probably others but you get the idea. Any screw that screws into a metal part. Not to include the metal nuts with the nylon inserts.