I have got a Teagle Jetcut Hedge Trimmer from about 1953 which is chain driven. It has stood for 48+ years. I turned it over and had a spark so put fuel in it and with the aid of a battery drill, it fired up and run! Just unbelievable after all this time with nothing done to it. However, before I use it, I need to change the drive belt as it is over 50 years old. How do you change the drive belt? There must be a simple way (?) as the only way I can see is to dismantle the machine. Any help is appreciated.