Datasheet
Start by sliding the 10 pin, 2 x 8 pin and 6-pin stacking
headers into the outer rows of the shield from the top.
Then flip the board over so its resting on the four
headers. Pull on the legs if necessary to straighten them
out.
Tack one pin of each header, to get them set in place
before more soldering. If the headers go crooked you
can re-heat the one pin while re-positioning to
straighten them up
© Adafruit Industries https://learn.adafruit.com/adafruit-motor-shield-v2-for-arduino Page 19 of 43