My Imagine 50 had the balsa still sitting in the slot when I cut the covering away. I thought that no slot had been carved for the vertical stabilizer, but it turned out that I just needed to pull the filler piece out of the slot in the fuselage. They back it that way to prevent damage to the tail of the fuselage during shipping.

[youtube]http://www.youtube.com/watch?v=70JB1ubXJko[/youtube]