Craftsman, Walbro 424C venting issue
My Craftsman leaf blower starts OK, runs for a minute or two and then slowly dies like it is starving for gas. When I push the priming bulb, a small amount of gas sucks out of the tank into the bulb, but then the bulb gets hard and does not push gas into the carb. I removed the carb, pushed the bulb and the small amount of gas that was in the bulb, did not push out. I rebuilt the carb this winter, but I am having the same issue before and after the rebuild. I cleaned the metal parts in Berryman's carb cleaner and blew compressed air through the passages. What passage(s) would be blocked that would prevent gas flow? I didn't replace the welch plug because I wasn't sure if I would install it properly, but I don't know if that would cause this issue.
Any thoughts? Much appreciated.