Using a radiator hose removal tool, un-pinch, open up that track. Making it looser rather than tighter will make install easier. The track can always be made tighter after install with a hammer and a block of wood. And, if you look at it a bunch, you'll see the factory pinched the ends of the track after install to help retain the rubber. Top to bottom, side to side, both sides, widen that track!
The sliding install is better on fresh paint. Either way, de-grunge, de-friction, de-rust the track with a wire brush, rotary abrasive pad, files, fine sandpaper, pick, whatever you can fit in there. Don't skimp on this part of the process. When you think you're done, do it a second time and catch all the stuff you missed the first time. Attack it like you're prepping it for a world class paint job, whether you're painting or not! For the non painters, this is a good place as any to start the rubber install. For someone who isn't sure, tape/mask around the track and grab a can of your favorite gloss spray can. Gloss slides better than primers, that's for sure. For those doing a full on interior paint restoration, proceed as usual.
At the dash, do the best you can. Opening up the track is better than not opening it up, even if you can't get a brush in there to clean it out.
My lube of choice was Joy Dish Washing liquid. Start with the forward part of the install as it is the toughest having to deal with the dash. Lube the "T" and the track. Start at the top and push down, gravity is your friend. It's been a while so I don't remember the particulars, but if you need to fold rubber near the dash, fold towards you, you are about 2' from the bottom? Grab some lube and lube about 2' of folded rubber flap. Then pour a little on the rub area of the dash. Push and feed until the is an inch or so of rubber coming from the bottom at the floor. Repeat for the back of the door. Make sure there are no twist in your rubber, that it is laid out like it is supposed to sit in the opening.
Now the most difficult part of the install that I found to be. It can be done either way, but always knowing gravity is my friend, I believe this is the way I did it. Hook the bottom of the "T" into the upper track. I'm left handed, so I started on the left side. Roll back the long flap and push the top side on the "T" into the track using the radiator hose tool. I've found that the perfect tool for this job, because it doesn't have as sharp a point and doesn't tear things like other similar tools, is the MAC SW70A. A little pressure with your thumb on the outside while folding the "T" into the track helps. Work it 2-4 Inches at a time.
After the top is in, adjust the sides as necessary, while they still have lube on them, to remove any kinks or wowies at the front and rear turns. Nice thing about doing the top, it allowed time for any excess lube to drip or travel to the floor. Trim the bottoms to where you want them to be. I like trimming them a little long then pushing them up into the track a little incase I stretched a section a little too much.
Get a small chunk of wood or a fat punch, and pinch both sides of all track ends. I believe I also pinched every foot or so. Except for maybe the top section. It should be fine. That involves pulling back the flap and the bulb to get to the track. Be careful when you do this so you're not pulling the "T" out of the track. You worked too hard to get it in there.
Damp cloth to clean up the joy. Then check back a day later to see if you need to clean up more. Lube, along with gravity, is your friend. You can never have too much lube. Don't cheap out when it comes to lube, but don't end up covered in silver like people do when they touch a bottle of anti-seize.
