to find that exact spot referred to above:
either turn the waders inside out and hang them from a very strong place like a deck railing or swing set--not the shower head. take a hose and fill them with water. observe closely in the region where you suspect a leak. mark where you see the water oozing out. a Sharpie pen works. dry and repair with aquaseal.
or turn the waders inside out and hang them somewhere you can get everything wet. thin some liquid soap with water and have it handy in a spray bottle. turn the hose around on the can vacuum so it blows, insert the hose into the leg of the waders, and hold the top closed with one hand. with the other, spray the liquid soap/water where you suspect a leak. mark where you see bubbles happening. rinse, dry, and repair the waders.
when you're done, buy some Revivex to renew the water repellent outside finish. spray the clean waders and finish with a hair dryer to heat-set the new finish--DO NOT put the waders in the tumble dryer or you'll cook the feet.
there! just like new...
took me a couple of tries, but it was worth it because ladies' waders that fit are hard to find
fly fishing and baseball share a totally deceptive simplicity; that's why they can both be lifelong pursuits.