At a "local" flea market yesterday I bought this Crosman M4-177 cheap because it wouldn't shoot. I took it apart last night and removed 3 stuck pellets from the barrel. It shoots good now.
I suppose someone had taken this gun apart before me because there are "slots" for two of the weights, but only one weight. If I had been more confident that what I was doing would fix the gun I would have done a little more cleaning and lubricating before I reassembled it. But it will be ok.