By the way Johnny, I found when using my crosscut sled that there is a "sweet spot" for where I put my hand to push. It's just off to the side of the runner a little and varies slightly with the size of the piece on it. If your runner is too tight it will bind and then you can induce torque trying to push which can make an irregular cut. i think it's more important to find that balance spot than it is to try and remove 100% of the freeplay.
Someone I consider a master woodworker once told me that a master woodworker is not someone who never makes mistakes. He is someone who is able to cover them up so that no one can tell.