There is a link for user to download EJS source in the first message.  Click the link and you can download ejs source
Then load it into EJS to modify or create new simulation (You will need to download and install ejs first).
You can also find java source code if you really need it.

You can also click [b]load ejs as signed applet[/b] button , EJS will be loaded into your browser (2M) so it take a few seconds for slow connection, then you will find all the code (you can modify the code and run new simulation,too!).