I have a 1954 2.5 HP Elgin Model No. 571.58401. While running, the motor shudders and recoils (or shakes hard) inconsistently but keeps on running. I recently cleaned the tank and lines but not the carb. Could this be trash left in the carb or an interal problem. It was doing it before I cleaned it. There had been quite a build-up of rust and sand like stuff in the tank.<br />Thank you steelespike for the earlier reply. That is a great resource.