I have an Arians rear motor Briggs and Stratton. One day when I tried to start it and after the first pull the engine locked up and could not pull the recoil. So from underneath I backed the motor off and then I could start it. The next time I went to use the mower the same thing happen again only this time the first pull would not pull. I back it off again but this time it would not allow me to pull the recoil. Has anyone had this problem? What was the cause? How did you fix it?