I have never had one of these apart, so can't say for sure what exactly acts as the mechanical safety on this gun. I looked a schematic and still can't say what exactly stops the trigger with the safety on. You said it has had a new spring installed? My first guess is that something may have been left out upon reassembly. If you don't want to take it apart, I might also suggest that perhaps the trigger adjustment could be a contributing factor. If the trigger adjustment screw is turned "in" (to shorten trigger travel, I believe), you might try turning it out and see if that helps. I had a Crosman whose safety lever was just sloppy enough that the gun would fire if I pulled the trigger with the safety on. It allowed just enough trigger travel (after doing a trigger modification) when in the "on" position that the gun would still fire. Since there is often just a little slop in most of the mechanical workings of (most) airguns, if that screw is turned in too far, or has been replaced with a longer screw to achieve more adjustment, it may already be putting too much pressure on the sear release when cocked. Just a little slop in the safety engagement, and the gun goes off.
