Power window coil broke.

My 1989 Cherokee's back right window works fine until it gets to the very bottom of it's track. Then it wont go anywhere and makes a grinding noise. I took off the panel and low and behold, the coil/spring looking device that the motor uses as a track actually broke in half.

What is this part called, and how do I replace it? Thanks.

They rust and rot through. The reason I force grease into the slot in the steel tubing guide for the coil, most every time I have a door cover off. And check to see the rubber tube extension for the steel tube at the bottom is still connected and has grease in it. Helps them to last much longer.
Pull the assembly out and you can pry or drill the stop out. Use a battery to run the coil (cable) past the gear drive. Check the gear drive, they are often worn past usefulness.
I've found serviceable coils at the junk yard, I've never found them as a separate item to order.
I keep my eyes open for doors that have body work, the window assembly often gets replaced when a door is fixed. I've found near new ones on occasion. Replacements can be pricey.