Gave my twitchiness issue some though overnight. Figured the front end was where I should be looking for answers and thought a bit more castor could do the trick and also a bit more travel wouldn't go amiss either. So I raised the front some (1mm) and it sits a bit higher than the rear now. Another thing was that it looked like the shell was making too much contact with the tyres so I raised that up one hole on the posts.



That whole shell is backed in white, the black is from the tyre rub.