I am a mere occasional user, and I like my MS 290, but I just finished troubleshooting mine (wouldn't start after not having used it for about 6 months...)
I had left it drained and had run the fuel out of the carburator, my saw wouldn't even splutter when testing with a little bit of starter gas... Checked ignition coil gap, as well as plugging in a new plug and test pulling it - and was getting a good spark!
What was the problem? The boot of the spark plug wire has a wire that has a hook that is pushed into the spark plug wire and then twirled into a loop that will lock onto the spark plug,
and its connection to the spark plug wire was bad!
It would apperantly touch "just right" when I slightly twisted it to plug into an "external" plug, but not make the right touch when plugged into the cylinder! I ended up re-attaching the boot/wire in a "new hole" and it appears to be fine for now. (I hope it will stay that way... Do you guys have any
alternative recommendation?)
Like I said... Other than this - and the "rotting" fuel line due to the E10 ethanol fuel, I really like my saw and think it will probably out-last me