Blade placement locations

I bought a used Phantom 4 Pro. The directions tell me to mount blades based on the presence or absence of black dots on the motors. The dots must have worn off. There are none. Is there another way to orient… based on relationship to battery position or what not?

As shown in the photo below, the top left and bottom right motors have black dots.

Thank you so much!

Thanks so much!

Here is the link to the every thing Pro 4 including the User Manual from DJI…