Originally Posted by Stan B

The front seal is nearly impossible to get INTO the groove - does not require sealant - actually, a coating of silicone lubricant all along
the channel inside and edge is essential - it's a VERY tight fit - you
start at one end, get the lower part's groove over the lip, then start tucking
the top piece inside, "walking" it along, as you go. Then, when all in,
press or "creep" the entire thing back into the channel until you get the ends
even and the center notch (where the little guide snaps in) centered.

The back seal is a little easier, but you still have to clean out the
old channel, start at one end, stuffing the edge into and behind the
channel edge. Then, when both ends are even and it's not stretched at all
(it's gonna want to shrink, with age) - you have to use trim adhesive (I used
3M black) to hold the ends and around the curved corner, under the top
lip, including the very end. Then you use a very sharp blade - thin box
cutter, single-edged razor, or such - to vertically trim the ends to just meet
the side felts, at an angle just angled in toward the center by a few
degrees (the felts will end up angled in just a little at the leading edge of
the hole's corner turn).

The felts are aligned on the side mounts (remember what I said about
hammering the old "locating" protrusion flat, to permit the (new, wider) back metal edge to sit all the way "outward"), - not the little ones
which hold the metal strip "out" and keep it from moving inward. The new
strips are Wider, and absolutely fill the spacing between outer "box" edge and the edge ofthe sliding roof. That strip should JUST come forward far enough to meet the very end of the front seal (probably about 3/8" forward of the metal clamp strip's front end) and extend off the back of the clamp strip at the slide channel end by about the same - far enough foward to nearly meet but not pass under the place where the roof's metal comes down about 1/8". Cut felts to length with a razor blade first, then tinsnips. Mount the side with the thicker rubber on the center section UP, to seal best along the roof edge.
When you get them in place, take tension on the mounting screws (don't forget the back one in the middle of the plastic guide piece), then use some flat straightedge and a rubber mallet to persuade them all the way in, up
against the outer edges of the "box" - protruding no more than about 1/8", else they'll be too tight to allow the roof to slide along and pop up
inbetween them. You can measure the hole and the roof at three or four
corresponding points (the edges are NOT straight or parallel) and divide the
difference by two, to get the required gap to be filled (with the fuzz compressed).
Later,

Stan