Hi all, this is my first post as a newbie hope its the right section..Just bought a merry tiller rotavator 20+ years old but all in good nick, trouble is it starts first pull every time but when you try to rev it it keeps cutting out, i have had the air filter off to expose the carb and there is a part on top which has a couple of springs on it this keeps opening and shuts the engine down (hope thats clear..I can send pics perhaps) Doing my head in now I have had it running perfectly but now it seems the choke system is not balanced any ideas PLEASE!!!!