gun looks complete to me. i see 3 hoses and they are in the proper place. trilogies dont have separate 3-ways like most cockers, they have that part integrated into the front of the body, that way it cant come out of adjustment. the little o-rings could be dried up or need replacing though. take off the frame and that little rod will come right out.
also that model came with a regulator, not an expansion chamber. its adjustable, you just have to take the cap off the bottom to do it. its kind of a pain. if you do get it working and still want to upgrade it, id start here just for convenience sake. the stock reg does work great once its set where it needs to be and you can leave it alone from there and use the ivg to adjust your fps. (thats the thing in the bottom tube at the back of the marker that the cocking rod goes through.)
check out www.customcockers.com
. lots of info on how cockers work and tuning guides. cockers are super easy to maintain, the trilogies even easier. its just a big help to know what each part does before you start messing with it lol.