With unusually fine weather here in Vermont, I took the opportunity to replace all the weatherstripping on the windows of Vintage Thunder. The process is easy -- once you know how. So let me tell you how I did it.
PART & TOOLS: 3M Weatherstrip Adhesive, 3M Adhesive Remover, cordless drill, small round wire brush for the drill, 13mm wrench, flat-bladed screwdriver (large), an empty yogurt cup or metal coffee can, window gasket material (available from Airstream through dealers), scissors or carpet knife, latex gloves, stepladder (optional), chemical gloves (optional).
Step 1: Remove the window. On a 70s trailer with the "classic" style windows, you just remove an acorn nut on the support arms that lift the window. I used a 13 mm wrench. This is done from the outside, after you've opened the window fully. No need to remove the screens. Once the arms are disconnected, the only thing left holding the window in place is the hinge. Lift the window up as far as it can go, and it will drop out of the hinge.
Step 2: Place the window on a soft clean surface (I used a painter's dropcloth on the grass). Get a flat bladed screwdriver and work it under the old weatherstripping. Then work it along the weatherstripping to remove the bulk of it. This is the hardest part. You'll probably spend 10 or 15 minutes at this, less with practice.
Step 3: With an ordinary 1" paintbrush, brush on a coat of adhesive remover. I used 3M Adhesive Remover, which is great stuff for this job. Read the directions on the can! Don't brush it repeatedly, just dip the brush in a cup of the stuff, and run it along the weatherstrip & adhesive remnants. Then let it sit for a few minutes.
Step 4: Scrape the remnants off with the screwdriver or a paint scraper. It should come off easily. Repeat Steps 3 & 4. (If you are going to touch the adhesive remover, wear chemical gloves. It contains known carcinogens.)
Step 5: The metal surface should now be mostly cleaned up. Take a cordless drill with a wire brush attachment (available at hardware stores) or a Dremel tool, and run it along the metal edge to get it completely clean. This will also brush off the remaining solvent, so the metal will now be chemically clean. Dust it with a paper towel once you're done.
Step 6: Measure and cut a length of weatherstripping for the window you are working on. Allow a few extra inches to be safe.
Step 7: Read the directions on the 3M Weatherstrip Adhesive! This part is easier with a helper. Put a small bead (or thin coat) of the adhesive along the flat back of the weatherstrip. The weatherstrip will twist and make this difficult. Don't worry. Have your helper hold it up while you put the adhesive on. You will get it on your hands, so latex gloves are nice to have for this step.
You'll have to put the weatherstrip down somewhere while it dries. Just lay it gently on the dropcloth or any clean surface, and don't worry it the adhesive touches. You can fix any bare spots later. While you are waiting for it to dry, apply a similar bead of adhesive to the window frame.
Step 8: Orient the first few inches of the weatherstrip so the flat backside (where you put the adhesive) will go on the window frame, starting at the bottom center of the frame. Make sure the two flanges of the gasket are pointed outward and downward, not inward toward the glass. Now carefully apply it a few inches at a time, working your way around the frame. DO NOT STRETCH THE GASKET. Be especially careful at corners. Make sure the gasket is laying flat and not stretched or compressed. This is also your opportunity to add a little adhesive to any parts of the gasket where the adhesive came off.
Press the gasket down as it is applied, to help the contact adhesive bond. Your helper is invaluable here, feeding you the gasket and keeping the rest of it from touching until you are ready to apply. Trim off any excess length when you are done. If the last 1/2" inch isn't sticking, just put a dab of extra adhesive on it.
Step 9: Put the window back in, and close it tightly for 2-3 days. This will ensure the gasket seats the way you want. Some windows might not want to close without someone pressing on the outside to "squish" the gasket. That's normal.
I did all five windows on Vintage Thunder in an afternoon, with a helper for the tricky parts. On the next nice day, I'll do the refrigerator access door (it takes the same gasket), and the entry door. Take your time and good luck!