I’ve just remembered that these things come fitted with a floating dip and went back to re read your post and see I completely missed the bit that you replaced it because the ball was sticking and giving trouble.The other mod I did was to the dip tube/hose that comes with the pressure lid kit. The silicone hose attaches to the underside of the lid by fitting INSIDE a small length of tube (that is identical to a gas dip tube out of a corny keg) and floats on top of the wort/beer by attaching to a stainless float. This allows you to draw the beer from the top of the fermenter (which is clearer), but the ball has a habit of sticking to the sides of the fermenter, which sucks up a bit of crud, and the hose VERY easily detaches from the float and the tube under the lid. If this happens, you can still get the beer out via siphoning, or through the dump valve, but both of these are less than ideal.
The float I use is a Cask Widge and has never stuck to the side of my 15 Gallon corny. I bought it in the UK a few years ago but thought I saw that one of the site sponsors stock them here.
Here are the spare floats on the UK website: http://www.caskwidge.com/shop/index.php?main_page=index&cPath=7&zenid=lYXHXkbd6FU8sKDkmSi5x1
they also have a ss hop screen fitted.