Did you attempt to remove the old carbon by clipping it off like shown in the eBay video, or did you just clean it?

It's been very hard to get anything to stick to the old surface, so, it'll be interesting to see if this method holds up.

I may give it a try.

fwiw, the MX-900 is a nice replacement for the MX-800/850, but it does take some work to bring a configuration over from one to the other due to the new file format and button layout.