If you like the recorder, wish to continue using it, and are willing to put in a little work to fix it..
99% Isopropyl alcohol, a rag and copious elbow grease will probably remove the failed and now sticky rubberized coating. Takes a good bit of rubbing but has worked for me on gear that suffered the stickiness problem, with the end result being a clean and smooth black semi-matt plastic finish of the underlying surface. Haven't tried it on R07 but it worked on other and could melt plastic parts. Test to make sure it doesn't before going hog on it with that stuff. Acetone will almost certainly remove the sticky coating easily but is even more likely to remove lettering and melt many plastics. Tread with caution with solvents other than 99% Isopropyl alcohol.
As for the button lettering, if you need to replace that (rather than just memorizing which is which) you might: print and cut plastic labels to fit using a label maker, engrave them with a hand-engraver, or use heated letter punches to lightly melt a letter into the surface of each button. I've used all three methods successfully.
Impermanence.. some things are more impermanent than others. Unfortunate, but these kinds of fixes have in the past doubled the lifespan of working gear for me.