This morning I decided to swap wheels and tyres on the 690SEL to try and find out where a 'tap tap tap' noise came from (it had developed after the day at Oran Park in November).
I was almost sure it was tyre related as it almost disappeared at higher speed (or it was drowned in road noise).
I did the usual hydraulic lock (centre position) on the dash and proceeded to replace the rear wheels first as I thought they were the cause of the problems (see pics of...