I had a few apps originally purchased through the App Store that got corrupted. I removed them with the intent of re-installing them from the App Store, but it seems that the App Store thinks they're still/already installed. The action button is disabled. I found How can I reinstall an application that the Mac App Store thinks is installed already? but the solution reported there didn't work for me.

The app doesn't exist in either /Applications or /Downloads. Do you have any idea about what I might be able to do to re-download the app?