Defect?
If it was me I would take the fuel line off the pipe and blow in that and see if you can push fuel into the carb. If it still won't go in I would look closely at the fuel nipple on the carb and see if maybe it is clogged or doesn't go all the way through. Never heard of this before but that's the only way I can think of fuel not going into the carb. You can also try pulling the carb off another rossi motor and trying to narrow down the source of the problem.