My Toro started dying after an hour, thought that was overheating but turned out to be dead insects in the fuel tank. Somehow despite all the bouncing around they somehow took almost exactly the same time to block the fuel outlet each time. No I didn't believe it either but that was definitely...
Ive managed to kill three Ryobi strimmers. They get harder and harder to start and then a compression test shows lack of compression. Sometimes you can see the piston is scored. Not sure why as I use fuel filters and the right amount of oil. Someone once suggested its important to let them warm...