It's funny how AA figures seem to be neglected these days, even with some percieved aversion to them from the imagineers. If I recall correctly, Walt was so excited about AAs because (among other things), they were performers that never need a break (figuratively), or a paycheck, or a union. In the 60s they were the perfect solution to shows that called for actors to perform all day. Now it seem slike they're almost as high-maintenance as live cast members.
Considering that most of the AAs in SM came from the America Sings attraction (unless they've been replaced with more modern figures), it's not surprising that these things, now pushing 40 years old, need constant upkeep.
Combine that with the "AA explosion" that occurred in Disneyland between 1963 and 1973, I would imagine that the figures from those times are breaking down with more frequency and requiring more time and resources from a service department stretched too thin as it is. Sure, a great many on the most popular attractions have been replaced, but I would imagine there's still some old clunkers around the parks.
Splash Mountain is such a wonderful attraction I hope they don't let it go to pot, despite the monumental task of keeping up all those figurines.