Ok guys picked this little baby up at a yard sale for 5 bucks. I figured you cant have enough mowers so i got it. I took it home 2nd pull it fired right up. I changed the air filter and spark plug and mowed my lawn. That was about 3 weeks ago. I had it in the back of my shop and decided to pull it out again. Now no fire. whats wrong???? any help will be greatly appreciated.