My 11 yr Ms291 has been to a shop one time, prolly 5 yrs ago for a check and tune. That shop is gone now. Months ago I noticed it was running a but rough but kept running. It got a lil worse so I took it the local Stihl tech guy @ Northerntool in Cary. A guy behind the window to the engine parts/etc. He said they were a month out for working on any engine. While I talked to him the Stihl mechanic walked up and I told him it's running rough and I need it now. He grabbed it and cranked it and ran it about 3 mins. and adjusted the carb and now it's running great again. I asked what's the cost? He said nothing and I told him I got cash, he wood'nt take it. Eddie @ NT is great guy !