Don't forget that a lot of these figures aren't the originals. They've been repaired and have had parts replaced. It's a case of the Animatronics of
Theseus.
Interestingly, there's been several articles floating around about the difficulty that museum curators are having with plastic used in art pieces from the 60's and 70's (and presumably, soon, the 80's and 90's). The plastic just degrades. Some become brittle and crack and break apart, some turn into a goo and just melt. How do you preserve *that*?
So, these creations are always in the process of deterioration. Especially the ones that had repetitive movements 16 hours a day every day of the year. Some were refurbished nicely, others withered. But, even the ones that were refurbished well (and, Theseusly, ain't the originals) will wither away, even when stored in a climate controlled warehouse (let alone a tent without any climate control).
Sic transit gloria mundi.