Today I got a closer look at the busted dusty.
The case is split at the top. It'll be tricky to fit it without taking the whole thing about apart and refolding it. I'll need to either bend the fold back up and pop it into place, or refold the entire section. I'll seal the inside with silicone or epoxy.
The impeller was simply held in with a single bolt, so was removed easily. There are two blades affected. The steel is painted and about 5mm thick. I tried to bend it by hand without a budge. Unfortunately the blade is studded on so I won't be able to remove it. (I thought it was simply bolted). A bit of heat may be helpful.