I have a lawnmower with a Briggs and Stratton motor, model 128T05-5268-B1. This motor was equipped with an electric starter, but the starter, battery and all the wiring have been removed. I start it with the pull cord. The mower will start, but it is reluctant. I have checked the choking mechanism - it seems to be working properly When hot the machine sometimes starts right up, other times it fails to start at all. When cold, if it is not cooperating, starting fluid does not help. The carburetor has been checked and cleaned. All seems well in there. Once started, the motor runs strongly.