How to open a Peachtree Nova?


I like to change the tube in Peachtree Nova but can't find the way to open it. Somebody help me?

Thanks in advance.

Jason
vsfang
I do slide the interior by pushing from the back .Like Danlib1 mentioned , the paint chipped on the front edges.I ruined the case and it's the price of tubing the Nova. Damn it!!!!
Vsfang; do you have the chips? A little elmer's white glue applied judiciously did the trick for me. The 2 chips glued right back in place and you can't even see where it happened. The Nova is wonderful, but the black lacquer hanging over the case lip is a ridiculous oversight in manufacturing. Obviously I was not the only guy that had the issue.
Is retubing the Nova really necessary? I mean those small tubes they use do last a very long time. It's not like power output tubes that have a much more limited life span. All the effort and risk of damaging the case is likely not worth it if the tube is working, right? I'm thinking about getting a nova so I ask this question. Last think I would want to do is have to open the case and retube the thing.