Not an experienced repair guy, but I have put seals on a couple different gliders. This is how I do it:

* Sand the adhesion areas on both the wing and the underside of the mylar 220 grit.
* Degrease both surfaces with acetone. Repeat as necessary if you happen to touch or otherwise contaminate any of the adhesion surfaces.
* Apply the adhesion tape first to the wing, leaving the protective strip in place on its back side.
* Lay the mylar in place and shift it as necessary so that it is perfectly straight along the wing above the adhesion tape. It is very stiff, so the slightest deviation results in a kink that resists conforming to the curve of the airfoil.
* When the mylar is located properly, temporarily tag it in place with bits of masking tape or glider tape every foot or so.
* With the mylar tagged in place, flip the mylar forward over the tags, using the tags as hinges. Then tag the mylar down in this position with a few more tags of tape.
* Peel the protective strip from the adhesion tape.
* Carefully flip the mylar back over onto the adhesion tape, taking care that it arrives in the position where it was originally tagged down.
* Use a small ball bearing, or better yet a pair of ball bearings (I use 626 bearings) bolted to a handle to aggressively roll the mylar down onto the adhesion tape, and the adhesion tape down onto the wing. You should see the color change through the mylar as you get full contact between the adhesion tape and the mylar.
* Remove the temporary tape tags.
* Apply the thin white PVC safety tape along the leading edge of the mylar so that it is half on the mylar and half on the wing.

JJ has done this much more than I, he probably has some additional advice.

--Bob K.