I had the door card off to repair the door handle - broken casting in the handle where the "reverse lever" attaches - more on this in another thread.
While I had the door card off, I decided to investigate why, with my window cracked an inch or so, it sounded like the window was about to fall out of the car when I closed the door. My window looked a little high in the back and low in the front, so the window glass was not square in the window channel. The low front appeared to be the cause of most of the noise. I searched everywhere (Clarks, PP, RL, YT, 924org, FSM, PCNA) and could not find instructions for window glass adjustment, and didn't really find anything useful, so I thought I would share how I made the adjustment.
I spent a little time studying how the regulator works and realized the three screws around the motor (2 over, 1 under) hold the regulator assembly to the inner door skin. The two rearward screws (circled in the photo below) are for window glass adjustment. With the window down about 4-6 inches, I loosened those two screws and observed what the window glass did when I moved the screws up and down in their vertical slots, both individually and together. I ended up with the rear screw down in the slot, and the forward screw up in the slot (your results may vary). This lifted the very front of the window and squared the rear of the window glass in the window channel. Now the door sounds solid, with the window in any position, when you close the door.
I forgot to snap a pick before I put the door card back on, so credit for this photo is from JohnJ's 924S Restoration thread (same car and color as mine).
I hope someone finds this useful!