Leaf Blowers

I have a 125B blower for two years now, only used in the summer. The end of last year, i started having trouble with it. When it is cold it will start using the proper procedure. When it warms up and you shut it off, it will not start, until it is completely cool. i have used the best plugs in it and they are gapped proper. The fuel is mixed as required, and air cleaner clean. What do you think ? Lee Olson