Thanks for your reply, I hadn't thought of anything like that. The saw is only 2 or 3 years old and had little use, just for cutting firewood and doesn't get over hot. It won't even run for more than 5 mins before it runs down and stops. putting the choke on doesn't help. I have cleaned the filter in case it was blocked, it wasn't. It's very frustrating because it works perfectly at first.