Take 2 Rubber Bands and without twisting, loop them around the red end and slide down the catapult arm.
Give one simple twist, twisting both Rubber Bands together.
Feed them between the two round pieces (the joint of the catapult arm and the arm stopper). Sometimes this can be a little tight.
Lift the toy up so the bottom release lever hangs freely. Feed the rubber bands through the space between the lower round piece and the release lever.
Loop the rubber bands around the release lever and slide them toward joint at the front of the catapult until they rest on the indention on the underside.
Pull back the catapult arm , raising the release lever slightly so the mechanism catches in the groove on the spindle and the groove on the release lever. It should lock in place; adjust until the locking mechanism works. Test the catapult without ammo by pressing down on the release lever to ensure proper function.