From your description it sounds as the speed control lever circled in yellow may not be moving far enough in the reduce-speed direction for the kill switch to make contact. Take a look at the kill switch, which probably has one contact attached to the bent lever, and the other to the stationary plate that lever pivots on. See if the contacts are touching each other when you move the lever to minimum speed. That is what stops the engine: if they don't touch, it doesn't stop.
I think we need pictures of your engine's governor, rather than re-posting the previous pictures.
Last edited by grumpy; 17/01/15 07:59 PM.
