Got the ms 660 out today to cut some cookies off a stump. Starting ritual normal except it died as soon as it fired (second pull on fast idle). Okaaaay, never had that happen. Didn't sound like the motor seized. It just spun down like I flipped the switch. Go to pull again and the cord won't budge. Removed the cover and pulled the plug. Stuck my finger on the flywheel, rotated it, and piston moved freely. Then I pulled on the cord and easy movement. No feeling of any binding. Put everything back together and made my cuts. Is there something I should be looking for here so it doesn't happen again?