K1200 header pin headache

I’m having a really really rough time with the surface mount header pins on the K1200 watch. When I finally line the pins up as best I can, I solder one leg in place. Then I try to check their alignment with the top PCB. But even the tiny amount of pressure needed to put the top PCB on will break one of the solder joints and that header will be dislodged. Can anybody please give advice on how to solder and test their positioning without undoing my progress?

Dear,

You can do this as follow:

Tip: “later on, you will need to place the top PCB onto these headers to connect both PCBs.” Therefore, we strongly advise you put the headers in place and only solder one of the three pads. Place the top PCB onto the headers to check whether their position is ideal. If so, you may remove the top PCB and solder the other two pads. If not, readjust the placement of the headers until they are ideal, then solder them.

Best regards,
Velleman Support