I bought a new FS-80 Stihl weed eater about 3 weeks ago. I used it on some small properties for a day for about 2 cumulative hours .After returning from vacation, I used if on a a few small properties with no problem. When I got to a large property,I noticed that it would start fine at first but after getting hot,it would be difficult to start or not start at all until it "cooled" down. I changed to a fresh batch of fuel,even though the fuel I had was good. With new fuel, I still had the same problem. This morning, I readjusted the H, L and idle knobs per the owner manual instructions. I seems to be a little better , but not as good as my other Stihl FS-80 used to be. Is this a break in period I'm dealing with or do you think the carb is a lemon??????