Just bought a used 2001 Walker 12 HP mower. First couple of cuts were good, no problems except getting use to the controls. Yesterday I was cutting 2 acres of tall grass, up a small hill. All the grass and dust was getting everywhere and I noticed smoke off the muffler. I shut down and found the GHS system was clogged, which I cleaned out. Now the mower won't start at all. When I turn the key I can hear the GHS shoot moving, but the starter does not engage. Also, the mower is facing down hill. When I put it in neutral and release the parking break, it does not move. Any suggestions?