The secret is aligning the king pin to hole its bolt fits through in upper cross head. If brake reaction arms are fitted loosen chassis mount end as the bolt has to fit through hole in kp end first. If you have adjustable camber version ensure the two washers that bolt first fits through are greased and fitted with shaped part against each other.
Buttons suggestion of using a tapered guide to align is probably the best although not much clearance above so it would need to be short. A screwdriver to align is not really up to the job. Ensure whatever tool used, it doesn't drop out of sight into threaded hole. I used a large allen key that snugly fitted into threaded hole in kp, moving it carefully side to side and front to back whilst nugging spring assembly with soft mallet until I was happy kingpin was centered with hole. If bolt doesn't fit easily to touch kp threads you haven't got it quite right. Never even dream of using a hammer
