I also purchased an electronic manual for my engine from http://www.tradebit.com
I was skeptical of these sites but was relieved to find that it was actually helpful. It cost me $5.99.
The interface is a bit clunky, but it works.
I suspect you have a problem with your needle/seat. Either the needle is stuck, or the hole is clogged and won't let it seat properly, or something's awry with the float that is responsible for seating the needle. If the the need can't seat, fuel can't be stopped from flowing into the carb.