Look at the backside of the sunroof cut-out to locate the point where 2ends of the old seal meet. At this point, carefully peel away the seal. Use a gentle cleanser to remove sticky residue from the aged sunroof seal. Avoid using a pointed object for this purpose to prevent stripping the paint.
Use a permanent marker to target the midway point at the backside of the sunroof cut-out.
At this point, start applying the seal that you had purchased from the auto parts store. Peel a small section of the backing tape from the new seal and secure the tape at the halfway mark to prevent it from sticking back on the seal. Press on the revealed section of the new seal, peeling away more backing tape in small sections as you go. To ensure that water does not drip in through the seal, make sure its wider part is facing upwards.
Cover the cut-out’s edge by attaching seal around it. Make sure that the level of the seal is snug with the sunroof. Make sure that you do not over stretch the seal while applying it because the length of the seal would be more than you need. Furthermore, apply the new seal in a straight line.
When you reach the point where you started applying the seal, there might be a small overlap. Use a cutter knife to get rid of the overlap by cutting at the edges. Just make sure that both ends of the seal fit snug with each other.