Hell Wojtek looks like you did it already for GlennThe main problem is the chord of the horizontal stabilizer. It should be more large. The leading edge of the stabilizer should start at the front hole in the fin. The slot was for getting set of the attack angle of the stabilizer. Therefore the way to get it sorted out would be to cut the stabilizer into two parts along its span and add the needed piece of plastic in order to get the correct dimension of the chord. But it is fixed now and you may remove some of plastic at the back and top edges of the slot toward the leading edge of the stabilizer and add some of plastic to the front and bottom edge of the hole, Of course the general shape of the slot should be kept. Also you may add some of plastic or a putty to the leading adge of the stabilizer in order to make it more overlapping the slot partially..
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