- 1). Stop the engine and disconnect the spark plug wire.
- 2). Remove the string head.
- 3). Open the head by pressing down on the latches on each side of the head. The contents are spring-loaded. Keep your hand over the contents because the spring and bolt can be easily lost, particularly in long grass.
- 4). Remove the string head cover, knob and spool and set them aside while you restring. Remember where you left the pieces.
Source...