12.) Generally when you buy a new power seat gear, it will not come with the threaded rod already attached, so you will have to carefully use some sort of bench press or clamp to press the new gear onto your old threaded rod. I didn’t have to do this step because I purchased my gear already pressed onto a new threaded rod from a forum member.
13.) After you have removed the broken pieces of the old gear from the gearbox, you are going to want to reinstall the threaded rod and new gear into the gearbox like so:
14.) Now make sure you lube everything up nicely (get your mind out of the gutter 
), and put the gearbox back together. It may take some effort to get the gearbox face back on, so just wiggle it and play with it for a while until it snaps into place. Then re-install all of the screws (remember that the 2 longest screws go on the bottom):
Now re-install the motors starting with the lower one first, then the upper motor, then re-install the plastic kick plate which is held on by one torx screw. Put the seat back into the car, or in my case just flip it back over, then re-connect the 3 harness wires that you removed earlier. Now bolt the seat back down, re-install your battery cable back onto the negative terminal of your battery, and enjoy fully functional power seats again.