I have the same snap fitter as brubendall and I haven't had a problem yet. They have easy to follow illustrations and rubber rings to kind of hold the parts for you to set them. I do suggest not squeezing too hard so you don't squish the parts and to set your snaps on an interfaced piece of material especially if it's a thin cotton. Hope this helps
You all have given me the urge to try again. I did not have a good experience the first time I tried these pliers.