Purchased the trimmer late last summer and obviously haven't used it that much. It started bogging down as if it were getting too much fuel when I went from half-open to full-open. It wouldn't rev up and "open" up like it used to. It was just slapping weeds around and they were bouncing back up laughing. The repair shop said; There was too much oil in the system/line. Because I took the guard off, it was running too rich because on occasion I must have let the string get too long and make the motor pull too much trimmer line around causing it to run too rich. Fuel was mixed good, settings were fine, just it was running too rich due to the guard being off. The funny thing is, my line was only about 5 inches long. I don't remember ever keeping it much longer than that. Does this sound right?