This was not as easy as it seems. At first I just replaced the foam/film in the keys that were dead, only to find that after I reassembled the keyboard, more keys would suddenly die, or some of the repaired keys wouldn't work. In the end, I replaced all the foam pads. Sometimes, I had to replace a given key's foam/film a number of times before I got one that worked. Today, I finally got it to the point where all the keys were working properly.
Now it is working nicely, I really like this machine. Would have loved to had one of these in university back in the day. Of course I would have had to have been a lordling or son of some oil magnate to afford such a beast. Nevertheless, it would have been quite cool to have.