I just bought my first Mossberg 500 and picked it up yesterday. As I am inspecting it, I was testing the safety and the action lock lever--I wanted to pump the shotgun and inspect the action/chamber. However, the gun now appears "locked up". The trigger is in the rearward position and doesn't move. The action/chamber?? is only partially open. I can't pump the gun. This is true when in either safety position. The action lock lever is depressed but appears to be stuck. Any suggestions?