Pat,It seems the respones above cover more experience at repairs than I have but what does the manufacturer of your waders recommend? Good luck!
Simms recommends Aqua Seal. On the inside not the outside of the fabric.
For pinhole leaks spray the area on the inside of waders with rubbing alcohol where the suspected leak is. The leak will show up as a spot darker than the fabric. Smear a light dab of Aqua Seal over the spot, voilà leak fixed.