Do as Jeff said. If the Gamos are similar to the Crosmans.....which I think they are.....the trigger assembly might be abit tricky to slip back into the slot. Don't use force......the harder you try to shove it in the more difficult. I gently twisted, turned and wiggled the assembly and it went in.
Make sure the sear (#2 in the photo I attached to this post) is outside or the chamber before you slide in the spring or it might get caught in the coils or you might break it. You can press it outward or upward if the trigger is facing upwards with a finger and then tie it in place with a twist tie or little wire.
Once you use the spring compressor to push the spring and the end piece back in...tap the pin in to hold the spring in place and then use "that" bolt....the one with the cube end to screw down the trigger assembly. In the Gamos there is an extra small thin piece of slightly concave metal with a hole in it.......that metal goes inbetween that bolt and the receiver. And then there's the small piece of plastic that goes in-between the (held down now) trigger assembly and that bolt. Remember to un-tie the sear. Good luck...and I hope this helps you out abit.
