I have a 2009 lawnboy walk behind mower with the B/S engine model # 124T05. The problem is, it starts easliy and the stops after about 2 seconds, but if I hold the choke closed 95% it keeps running like a champ, Any ideas?

SOURCE: Lawnboy model 10640 walk-behind mower

I have the exact same problem. I read on another site that the blowout hole in the back of the mower where the grass goes into the catcher must be cleared of any grass or dirt. I don't use the grass catcher and indeed the hole was full of dirt and grass. I cleared out what I could with my hands and a screwdriver, and magically somehow the cord retracted about a foot. Enough to start the mower with. It still doesn't retract all the way, but it was an improvement. I may have worn out the spring pulling and tugging on it trying to get it to retract, but ok for now.
Please share if you find a more permanent solution. Mower is barely a year old.