I had a older fs 76 linetrimmer it got to where you constantly had to mess with the choke to keep it running.Seemed to run best at about half closed. Was not carboned up,got rid of it. I got a hand held leaf blower fs 55 i think two years old now it is doing the same thing the choke has to be half closed for it to run then it is at about 80% .Nothing looks carboned up.I took it almost all apart.My echo stuff runs ok.Not bashing stihl it just seems strange that both stihl products did the same thing.I would like to no what is wrong and fix it? Our local dealer rebuilt carb(?) on fs 76 did not help at all, got mad gave it away.now leafblower same thing.I use stihl oil .No problems with husky chainsaw neither.