Something of a late reply, but I have a Dufour
35 Classic 1998 with a Whitlock Cobra steering system. Shortly after I bought the boat I had a problem with the steering which may be instructive.
suddenly developed very excessive play and seemed loose and un-engaged with the rudder
. We got back to the mooring
but steering was very approximate.
Investigation revealed that the 12mm bolt that tightened the clamp on the rudder
post had sheared off inside the rudder arm. A new bolt fixed the problem and it has not returned.
At the same time we replaced the couplings on both ends of the draglink as the bearings were also worn and had excessive play.
None of this was reported on by the marine Surveyor
who did the pre purchase survey
Hope this helps
PS - not a bad idea to check these sort of things occasionally.