HP-28S: Key press problem

[JDW]

I've been using my 28S since 1990 so it shouldn't come as a big surprise it now has a key problem, but I am posting this to see if there is an easy solution. The UP ARROW key is the problem. When the calc is laid flat on a desk, no matter how hard I press that key, nothing happens. But if I press softly on the key front and back, it works fine. Saying it another way... Pressing straight down on the key (the normal way to press keys) does not work, but applying pressure from the top and the bottom (finger pressing on back of calc, directly behind the key) works.

Is this repairable?

Thanks.