If the bead is small enough to go through the hole, it won't help -- it'll just tend to pull up through, even when wedged by the pin. I suppose you could get just the right size bead, or even use a string ball (good luck fitting one on the sixth string), and the difference would be that the string is held further down, but you still have the problem of the chewed-up plate holes.

Sorry, that isn't the real answer. It's just a stop-gap, easier than a new plate or the suggestion above, but you're out of luck if you lose or break a bead (and how much tension could such a small wooden bead withstand, anyway?).

Bob