Hey Buck,
You can also use a piece of neopreme, instaed of canvas. I used a section out of an old neo gravel guard. With the neo cement applied to both the waders and the patch, allow to get almost dry and stick'em together! Mine never leaked after that. I only use breathables now but got a leak in the seam in the same place with those too. I used "Aquaseal" on them inside and out, no more leak! cool