It is recommended that all engine controls be replaced in conjunction with the maximum time between overhauls for the engine they are paired with. However, you may find that over time, the friction lock mechanism on your McFarlane throttle control does not seem to hold its position as well as it did in the past. We have a solution for that!
To learn more, please read Extend the Life of Your McFarlane Throttle Control by Matt Sharpton, A&P Mechanic.