I bought this to fill up one of my HK orders. Here is how i put it together
The parts in the bag.
The linkage endings. Press the little metal balls into the plastic.
Put them on the shaft like so.
Grab two servo horns like so.
See if the holes will fit the bottom piece like so. If so, then use screws to hold the horn on to the piece. If it doesn't fit, you will have to use hot glue to hold it in place.
Testing with a servo. Make sure you center the servo somehow before screwing it on.
Put the bearings in to the arms. Everything is press fit. Now, insert the camera mount plate into the bearings.
Put the little bearing covers on.
Once you have that, carefully spread the arms so that the base plate fits in (see bottom).
Put the servo arm on with the servo centered like so.
Use the itsy bitsy screws from the pack to attach the linkage to the servo arm and the base arm. i used a spacer on the servo arm for better movement. To get the angles right, i held the servo to the camera plate with my hand, and then used the HK servo tester to see what range the servo moved the camera plate. Then i moved it a bit up or down and repeated until the camera plate moved in a range i wanted.