My Crosman 1077 fired fine for about a year. Recently when I tried to fire it, I was unable to do so.

The trigger does not move when the magazine is fully inserted.

The trigger moves fine when the magazine is not inserted. (Of course, it fires only CO2 without the magazine.)

I'd appreciate any suggestions anyone may have.

Check that you moved the sliding pin fully to the right when you put the round magazine into the clip.

Also, check that the barrel lock (wings on the sides of the receiver) are in the proper (locked) position.

Your analysis was entirely correct, Four Eyes.

I wish that you had written the Owners manual. Perhaps Crosman should create a detailed on-line "troubleshooting" guide (not the one that comes with the owners manual) that incorporates/indexes the lessons learned through this Owners' Forum. I should think that such a guide could only help sales.

Only a thought. In any event, thanks again!!!!!

If you find yourself in a fair fight, your tactics suck.