For a good repair, your kite must be cleaned and especially de-salted.
1 - Open the extremity of the strut, remove the scratch and take out the bladder.
2 - If it is a side strut just open the scratch, if it is for the central leading edge, open the central zip and pull the leading edge.
3 - Connect a line on the extremity of the strut bladder, to make sure you can slide the bladder back in place at the end.
4 - Once your repair is done, insert the bladder back by pulling the line; Make sure the bladder is as flat as possible to avoid twists.
Its easier to do it with a friend ( one person is pulling the line slowly while the other person is holding the bladder strait and flat)
You can finish by inflating the bladder slowly to ensure there are no twist.
For more help and more information about how to fix a kite leak, it is possible to contact Soulkite.