The swashplate as shown has short and long control arms. Take note of this for later in the thread as it is important.

Slide the swashplate onto the main shaft. Gently pull the swashplate anti-rotation slot rearward and insert the swashplate anti-rotation pin into the slot. This keeps the swashplate from spinning once the heli head is in rotation.

Now attach the control arms to the swashplate as shown in the picture.