Hello paulainscow,
I have had the same problem.
I have tried many setups and it did not help, the car ran well enough better but had the same problem.
until my car was in the hands of one of Schumacher's drivers.
he saw that my servo was plugged into the rear holes. so the link between the servo and steering Mouldings was not quite right, it was angled and were not straight.
He also found out that my battery was very light, they weighed 65g less than other drivers at my track.
so he line the link propper with the Steering Moulding, and add more weight in the back. (new batteries/65g more weight)
and now i was also able to lower my right height to 19mm, and even less is it was needed, now with the 65g more weight in the back
My K1 was like a new car, ran more stable, and now i was able to run my car fast in the corners without the backend spinning away.
I really hope this can help you, it surely did for me and my K1
From Kent H
Denmark