How do you repair a power window of a 99 miata that will not go all the way down?

Well, I had the same problem out of my Mazda... if it is the driver side, check the switches to see if the passenger side works. if from the drivers side switches one window works, and the other does not, you need to replace either the power window motor located in the door, or the switch itself. (But check the fuses under the dash first!) if no blown fuse is visible, then the motor is most likely to blame. I have had 2 mazdas with the same problem. good luck.