A replacement Governor Arm made of toughened steel.
Generator Guru says:
If your engine is revving, please check the following before opening the engine casing:
1) Check the spring on the Governor Rod. This is the rod that goes from the top of your carb to the governor arm. Check if the spring is broken, becomes slack or has come off at either end. Replace if necessary.
2) Check the Governor Arm spring. This sits between the engine and the governor arm. Replace if necessary.
3) If step 1 & 2 has failed then your governor will need resetting. This is a complicated job and we suggest is only carried out by a mechanically minded person. (You will need 2 people)
A) Person 2 - Pull gov arm to far right.
B) Person 1 holds with pair of pliers the governor spindle that protrudes from the engine, while Person 2 loosens the retaining bolt on the governor arm and lifts the governor arm straight upwards until it comes off. Do not turn the governor spindle while doing this.
C) Person 1 rotates the governor spindle as far clockwise as the spindle will turn.
D) Person 2 replaces the governor arm again in the far right position (throttle completely open) and tightens the retaining nut.
4) If the above steps haven't solved this, you will need to open the engine and replace the Governor and/or the Governor Arm Shaft.