I have a G5200 lawn mower that I can not get to turn over. It was just fine until I shut it off after cutting 2 acres of grass. I wanted to fill up with Diesel fuel for the next cutting. I filled up wit the diesel fuel and now I can't get it to turn over. As first I thought it was a safety switch, but tested all of them and they seems to be good. I had the battery and starter tested and all seem to be working fine. When I took off the starter and had it tested I reinstalled and it did turn over a little, but stopped. I don't know where to go for here please help. I live in the South West suburbs of Chicago.