I've got a Trim Rite 733 lawn edger for making nice lines between grass and concrete. It won't start. I'm no mechanic and don't really know where to start on getting this fixed. My mom gave it to me and it was running well a year or so ago but was stored with gas for 12+ months or so. I drained all old gas, put in fresh gas and cleaned the spark plug. I can't find a primer on the unit anywhere. I just pull and pull on the string and it won't start. What do I need to chack and how do I go about checking it? I can post pictures of the unit if that helps.