Engine used on my standby generator has served me well for more than 25 years. Then electrical power became more and more dependable, and the usage fell off dramatically. Trying to start it now (hand Crank), no sign of fire. Fuel is full but it has been there more than six months since the last time we ran it. Where should we begin to check out/discover the problem? Never had a bit of trouble before. It is inside and the temperature is in the 80s. Thanks men!