Another stupid question. In your pic they are connected to the back of the post. Is this how you connect banana plugs? The reason I ask is on my receiver I connected them on the top of the post. (i don't have banana plugs) Sorry but I'm a noob and i'm extremly confused on how you have your speakers connected.
These particular bananna plugs have a hole in the middle of the plug. You unscrew the top part and the hole opens up. You put the wire in and then screw in the top part until the screw compresses the wire and holds it in there. Very secure.
I had the same TV for the longest time and loved it to death. Unfortunately it took longer and longer to turn on each day and eventually the picture started to flash. I couldn't even bring myself to throw it away when I replaced it. Anyway, thats a very nice setup you have there.