I think I've seen the set-up before tiger, but haven't seen what is under the cowl. I think that knob is supposed to connect to the speed control lever on the governor. As on most similar Briggs engines, the speed control lever operates the kill switch as well as setting the amount of tension on the governor spring. It sounds as if that plastic knob is broken and now it isn't operating the speed control lever, which it should slide down onto as the cowl is fitted. However rather than taking the thing to pieces blindly, it will be better to do it already knowing for sure what fits on where. The IPL should tell us that, once we have the Model and Type.
