I have a Husqvarna YTH 1846 with a Briggs 540 cc 18.5 hp mower that will not start. The last time it was used it started and ran fine. I got off the machine to open up a gate and when I tried to start it back up it would not start. When the key is turned the motor will turn over slightly and then stop. The battery is new, solenoid is good. The motor seems to turn over until it reaches the compression point and then stops. With the spark plug removed the motor will turn over normally. I tried adjusting the valves with no luck. Is it the starter or some other problem ? Thanks.