I have a O.S max 46la engine that is only about 8 months old. It had been running fine but now when i get it started up it runs fine for a little while and then just looses all power. I can hear that it is not running right. I have tried to change the needle vaulve setting but that doesnt work. I have put a new glow plug and am running new fuel (10%) which is what i have always run.