I've done research on here and checked everything that I can think of as to why it's bogging down. I've checked: fuel filter, fuel lines, spark plug, exhaust being plugged, clutch or head issues binding it up. I have two of these trimmers and originally one was bogging down. It would run at idle, but when you pulled the trigger to wide open, it would bog down and only run slightly faster than idle, but the smoke would poor out. I decided to switch carbs with the other F 222 last night to see if that was the problem. With the working carb on the non-working trimmer it still had the problem. But, when I switched the working carb back to the working trimmer, it no longer would rev up. So now I have two F 222 trimmers that are doing the same thing. I'm guessing that I have dirt in the carb or something. Should I possibly buy a rebuild kit for it or buy the entire carb assembly? Any advise would be greatly appreciated. Thanks.