am having the same problem right now with my redmax weedwacker! the muffler port is clogged with buildup from the oil in the 2 cycle mix.... this has been happening to my trimmer 1-2 times per year for the past 3 years! my dealer told me when it happened last year not to use lawnboy mix anymore because its so rich but to switch to echo, so i did and now its happening again! starts in 1 or 2 pulls but dosnt even have enough power to cut grass!