I have a 20+ year old goretex jacket, but the tape seams are leaking as the glue/sealant broke down and the tapes simply fell off

As I have never seam sealed before I need some advice.
1. Do I need to re-tape the seams or will simply sealing them with silicon be sufficient?
2. If they need to re-taped, what can I use for tape? (the originals are lost/gone) I had thought of using tyvek but this seems very stiff and I expect it needs to have more "give" to move with the shell
3. Do I need to thin the silicon down with thinners/turps etc or do I apply it straight? If so, how thin do I make?
4. Any other advice?
thanks
rebro5