I was mowing today with my toro recycler model 20042 6hp GTS Briggs & Stratton engine when it just stopped dead. There was no warning such as sputtering. It just stopped like I hit a big rock, which I didn't, and the brake did not engage. I tried to restart it to no avail. Of course I checked the gas, loose spark plug wire, etc., but all was ok. Has anyone had a similar problem and found a solution to fix?