I went through this same issue last year. Look at Chapter 14 of the Mazda FSM. You can download a copy of the 1980 and 1985 RX-7 at http://www.foxed.ca
There are three bolts attached to the regulator. It's hard to describe the position without a picture, forum won't let me upload an image larger than 800x800. There are a pair side by side left of center on the driver's side, and one close to the front edge of the door below the height of the window winder. When you loosen them, the pair of bolts shift vertically and the single one shifts left and right. Those three bolts move very little, but they make a big difference. Loosen either the pair or the single one, move them a little, tighten, and then roll the window up and down.