I had a similar problem with my Win 94 30-30. I took it to the gunsmith, who took it apart, put it back together, and corrected the problem. In my case, the screw holding the gate in place had come loose, which allowed the gate to move back slightly. There are two tiny tabs at the front end of the gate that keep the gate inside the loading hole. When the gate moved back, it allowed the gate to pop out slightly, which resulted in a stuck gate.
It might be as simple as unscrewing the gate spring, making sure the gate is in the right position, and tightening the screw.
brad