So now I have the circuit board on my table. I have pushed the rubber pegs from behind, to loosed the rubber contacts.
I had no problem pulling up on them to pull them free, to reveal the electrical contacts beneath. Nevertheless, do it carefully, so as not to rip the rubber.
You may be replacing contacts in their entirety, in which case, you do not need to be as careful about ripping a rubber.
Take a Q-Tip, dipped in isopropyl rubbing alcohol, and clean the electrical surface points.
Also, run the alcohol along the inside of the rubber cups. Use the Q-tip to push the rubber molding back into form.
I believe my D# was stuck, due to a cock-eyed position. I spent a little extra time pushing the outer bowl form of the rubber cup.
The cup, is shown in this picture with 2 black contacts in it. There are a pair of them. Clean those, too.
When done, do everything in reverse to put it back together.