I have a HM-100 tecumseh with a barely legible model number. It looks like it ends with 8P. What I need to know is, what carb do I order? It's mounted in a heald vt-10 The carb that is on it is a #640152. It was brand new and the guy that WAS working on this project said he had to put two ball bearings in it. It will not idle. I do not trust the guy's judgement In fact, I think he really goobered it up. Oh well, any answers would be greatly appriciated.