I have the Dan Baileys and the seams started loosening a bit over time allowing small leaks so I took Aqua Seal and ran a bead over all the seams and pressed it in with my finger. Let it dry over night. Worked great.
You can buy Aqua Seal at any fishing store for about $5 a tube.
Also, to find leaks, fill up something with water...a trash can, the tub, etc. Get air in the waders, roll them up and submerge them looking for air bubbles escaping.