Small Engines (Lawn Mowers, etc.): Kohler tractor engine throttle wont stay on full, lever assembly, throttle lever

Question
The throttle on my Toro (Kohler Magnum 14) lowers itself as I mow.  The lever and cable appear to work properly, not too loose as far as I can tell. The vertical lever works its way down from the top (full) slowing the rpm's and I have to keep raising it.  Do you know how to create more friction or what is pushing it down?  Thanks

Answer
Usually there is a wave-washer (compression washer) as part of the throttle lever assembly.  Over time it can lose its tension and cause your problem.  Vibration from the engine running causes the throttle to move.  You will need to replace the throttle lever assembly to correct the problem.  Hope this helps.