[Hectic]

Once you open the gun the barrel will come out with the hop up unit attached there will be a lil c clip and some screws and such remove the screws and the clip the barrel and hop rubber will slide out (may take a bitbof pulling) the screws will remove the hop arm (the nub rests on that it may drop out when the barrel and rubber is removed) reassemble start by putting the rubber on the barrel and then insert in the hop unit then the cclip.
After that put the hop arm with the nub back in (i think its like the ak so the arm will stay attached to the unit) so slowly slide the arm into tue unit with the nub on it (holding the arm flat resting the nub and then tilting the barrel and unit onto the arm is easyest) once the arm is in push the adjuster lever on and ohld it in place while you put the screw in and away ya go