Appreciate the additional input. When we are idling, this is when the little 2 cylinder thumps. When we increase RPM's even slightly it all smooths out. It's very smooth underway. Sometimes if we need to idle for a while, we'll just increase R's to smooth it out. It idles easily but adding a touch of throttle smooths it out. Hm, belts. I've checked them annually. I'll check 'em again ! Thanks.
