[rescue] Disintegrating Type 5 Sun keyboard feet?

[rescue at sunhelp.org]

I've now got three Type 5 or 5c keyboards here whose
rubber "feet" are disintegrating, leaving sticky gray goo
on desktops and such.  It's annoying and I'd like to stop
it from getting any worse.

The best fix I've found for affected keyboards is to stick
a cut-to-fit piece of post-it note over the former feet...anyone
have a better fix (like a good method of replacing the
silly little things)?

And what the heck is causing the breakdown?  (what
substance should I keep away from the unaffected
keyboards?)

  --Rip