How did that happen? Your wall of vintage figures are all in clamshells. Did he drop the clamshell and the bubble still busted?
I store all my vintage figures in UV protected acrylic cases. There's no air, dust, or bugs getting to these and they could probably withstand being manhandled or stepped on. That said, Vader was about 5ft up on the shelf and I'm guessing that he opened or closed the door too quickly and caused it to fall. I even have carpet on the floor, which protected the acrylic case, but the force of Vader slamming into a 35 year old yellowing bubble was just too much.
I was pretty grumpy all weekend.
I looked at replacement POTF Vaders and they are crazy expensive. I think I've sold myself on getting a replacement bubble, trying to remove the old one and "re-card" it. It's the cheapest solution and the only one that let's me keep this signed card on display. Sam felt terrible and apologized throughout the weekend. He wrote me a really nice apology about what he did wrong and what he should have done differently, and then tossed in $5 to help me buy a new one. Pretty sweet for a 9 year old, and honestly I think any of us could have knocked the figure down. He's grounded from video games for a week for going in without permission and not telling me right away, but not for breaking the figure.