Since Stern revamped their website I've had to use the contact form to get stuff like this from them directly.
Looks like it's available online via "questionable sources" (i.e. you have to create some kind of account via some kind of service) to get it. I just searched for stern simpsons kooky carnival manual pdf download and got a couple of sites.
I'd try the direct route with stern first, or possibly go through a stern distributor. I sent Stern info when they revamped the website that the old stuff was just not there at all, they said they were in the process of moving everything over, but I think they just dropped the old info. Haven't checked in 6 mo. or so though.
