That repair kit likely has some black carbon film in liquid form. I don't think you can use that on the buttons themselves as they are a plastic/metal combination I think.
I would look for a remote on ebay with a broken screen or something that you can swap out the whole button unit with. Note that if your 9600 has a metal scroll wheel, I don't think you can swap buttons with a unit that has a plastic scroll wheel as I think they changed slightly.