At first I thought my rear wiper motor was out. I would rotate half way and stop. Tried spraying some lube on it, etc. Its not so much that it gets gumed up its lack of lube.
Pop the cover back.

Remove 1/2 nut.

Gently pry the arm off then gently pry the cap off.

Remove the c clip and washer.

Use a 7/8 inch deep well socket and remove nut.
Gently tap the bolt out with rubber mallet.

I cleaned it with brake parts cleaner and lubed it up. The rubber o ring was pretty worn so I replaced it too.

Reassemble and test. If the arm does not line up loosen the 1/2 nut and turn the inside part all the way to the left so that it lines up with the hole in the liftgate.

 

What the heck did you say? I can't even follow what the problem was.

 

The rear wiper wasn't sweeping all the way across the window, it kept stopping. The problem is the center shaft seizes up. He's showing you how to remove, clean, and regrease it to fix the issue.

 

Right. Posting pics eats up my patience but you need to know what pops off and what has to be unscrewed.

The rear wiper motor has enough torque to move the arm half way across the window then stalls. You can pop the glass and watch the motorized part in the liftgate return to normal position. I imagine a lot or motors get replaced when that is not the problem at all. The wiper arm looses lubrication and becomes too stiff to move. With the glass popped up try to move the wiper arm. If it is super stiff then the problem is lack of lubrication in the arm, not bad motor, fuse, etc.