Filed, deburred, and smoothed spar cap; rear spar doubler; rear spar; ribs; and front spar edges. Deburred all holes on the assembly. Ordered new vertical stabilizer skin. Previous builder had dimpled the skin. Found cracks in dimple edges from holes not being prepared properly. Although build quality was not good, the previous builder had only started section 6-2 and 6-3. The rest of the kit was untouched.