Crossman 760 Bb Gun I Have A Crossman 760 Pumpmaster Bb Gun?

I have a crossman 760 pumpmaster bb gun? - crossman 760 bb gun

The rifle has been sitting in my basement for God knows how long, and I've never shot. When I try to pump it is much easier, and not feeel it takes to the air. I oiled and not working, suggestions? So when I press the "lock" (the thing) with lead whith is an issue of "L", a) not all the way through, and b) when they reached the end of how to press The "L"? Another question I BBS into the hole on the side, and no cost, if I screw, what should they do?
Thank you for your help, JH III