I have an 8000 watt generator. The last time I ran it I tried to connect my central AC to it. It stopped running. I reset everything and it runs, but I have to 'pull' start it. It will not start using the starter switch. I have replaced the switch, and took the starter off and had it tested. When I try to start it I can hear the starter spin, but it doesn't seem to connect and turn anything. Any ideas? I have never worked on a generator before.