Yeah... if kicking it doesn't help, it's time to let somebody who knows what they're doing take a look at it.

About the only thing I would do is check the speakers to see if they're blown.
Just press down on the cone. If it sounds scratchy or doesn't move in and out smoothly, chances are it's burned out.

You used to be able to take tubes in to have them tested at the local hardware store, but I guess that was back in the dark ages when everything used tubes.