E120b not starting

Hi, my e120 was running fine then the next time I went to start her...turning over fine my 120 was running fine, then next day would not start, check the fuel solenoid, seems fine, have fuel at the back of the head, I am wondering it it is the little timing adjustment screw under the rocker cover, I had a problem with this before but am having trouble finding the correct way to adjust this in my manual, any help would be greatly appreciated...cheers