I bought a gas trimmer last week off Craigslist because my old electric trimmer died. It ran when I bought it. Now I can't get it started. Well, actually it starts but for only a second or two. Then it dies. The instructions on the machine say to full choke it, prime 10x, pull 5x, move choke lever to middle, then pull to start it. I don't have the manual so I don't know what to try if that doesn't work, and it's not working, because I spent 30 minutes trying to start it. My arm is sore from pulling the rope so much. It has gas and oil (4 cycle). What might be the problem? I am not mechanically inclined and this is my first gas trimmer so please be gentle! Thanks.