I do realize this is an older thread, but just went through something similar to this OP that might help someone in the future. I purchased a 98 from a little old lady and suspect the broken rear window zippers had not been zipped much in the 15 years she had owned it. The driver side back window was zipped mostly down with about 2 inches at the bottom open but had NO slider. One side of that end of the zipper did not have the starter piece of metal, insertion pin I think is the term. I wanted to open the back window, but how would I close it? There was no slider at the top or anywhere else. OK here was my method.
I suggest the first thing you do is go to amazon and order 2 of the new zipper moving part thingies (slides) for each side you will be working on and some stops you can crimp on. (not mash, really crimp, I have marks from my heavy wire cutters because the mashed ones were still loose)
My rear window is the original factory top, spiral size 10's. Then as they are being shipped, I suggest you go to google and search for "rare and uncommonly used cuss words", You are most likely going to need a few spare new ones before you get your zippers fully operational. I worked on and off 2 days before getting mine operational, But saving me purchasing a new top just to open the back window.
I am a Jeep newbie, had to figure out I could unzip the back side window under the Velcro and uncatch the corner piece by pulling down to get some slack to move stuff around for more working room with the zipper.
I used WD-40 spray with the little pipe thingie up and down the seam with paper towels washing the dust and dirt out of the entire zipper track. I then used one new zipper slider with the big end on first from the bottom with the tang side (there is a front and back to the zipper and the slide) to the inside with some small needle nosed pliers, first to pull the cloth with the missing starter piece through. Trying each side, my first zipper tooth on one side was bent, had to clip it off with some little clippers. Then used the small needle nose to help get the two sides of the zipper start clicking together. Yes very concerned having to peal open the closed zipper to run this one up with no way to close it if things did not work out like I planned. When I got the slide to the top and around the corner over about 8 inches, yes I was off a couple teeth on one side, so what? It is under the flap.
I then took another slider and ran it up backwards (small end first) to "unzip" the previous zipped one. I put a crimped stop on the side that the starter was missing after I got it up a little. Put another one on the other side as a safety backup. (if you have to go through this, you will understand why, you will never want to have to do it again) Now at the top of that zipper over about 8 inches around the corner I have the "repair" spare slider that performs no function, but I can use the second one to zip down the window zipper until it hits the stop to "close" the window a half inch from the bottom.
I have some very old "Stick Grease" used for car door latches, should not melt away in the sun that I ran up and down the zipper to lubricate it. So far it works well.
Bottom line here, I was very heavily considering purchasing a new top because of this back window zipper problem was on the top support side and just purchasing a replacement window would not have helped. Yes, it was tough to fix, but it worked. And as a bonus, After two days fighting this, if I happen to be around some one who prides them self of "cussing like a sailors", I can impress the hell out of him with my new Jeep owner vocabulary. Ha Ha
Good Luck to you.
