I received my Mossberg 51M today, which turns out to be an (a) model. It looks almost brand new. I do have a problem with it, however. The cocking handle doesn't seem to be retained as it should. I can pull it out no matter what position the bolt is in. I thought it was supposed to pull out only at the last opening in the bolt handle slot. Looking at the bolt handle, there is a groove that, I'm guessing, is meant for some retaining spring to fall into. The hole in the bolt looks to have a semicircular groove, which may hold a spring, but I think it's missing maybe. I don't want to fire this rifle with the cocking handle in it for fear of losing it.My question is: how is the cocking handle retained? I appreciate any help with this.