I bought a a husqvarna walk behind mower. HU625AWD.. I haven't even owned it for a month.. the bottom part of the mower got clogged with a lot of grass. It made a popping noise and then started smoking. What is wrong with it? I am letting it sit for the night to see if it may have just overheated as I had been using it for 3 hours straight before it occurred. However I am looking for suggestions as to what could be the issue if it did not just overheat?