just got an older model 160 .It had not been ran in two years,so I cleaned the carb and replaced the old gas and battery it started right up. The next time I went to use it I turned the key and nothing happens no sound at all turn the key a few more times and then it started ,this has been happening for a couple months now.Went out this week and it didn't start and still hasn't no sound at all when I turn the key.I have replaced the ignition,and wiring harness. Any thoughts as to what my problem is?