I have a single-handle Delta kitchen faucet that will not stop dripping. I did some research online and learned to buy a replacement kit to replace the interior workings of the faucet. I have done that, and have replaced every interior part, both O-rings, the springs and seals (which I am told is commonly the problem of dripping), also the black seal on top of the ball, as well as the white plastic shield on top of everything. The only interior part that is not brand new is the ball itself, however, it looks and seems to in fine condition.

After replacing everything and successfully putting the faucet back together it still continues to drip!

Any thoughts on what to do next to fix this dripping problem? Any help would be greatly appreciated.

The ball has a scratch in it. Replace it also.

If the ball had a scratch in it wouldn't that scratch be visible?