Dave ,

1) Whether cleaning took place or not it cannot impact on the RC dates of the antlers .

2) It is the non existent Z 8 which would be under the sarsen if the arc had continued , and because the irregular arc continues after 8 it shows that the fallen sarsen was in the way . Geophysical survey in 1994 found a couple of depressions outside the arc ,one being assigned 8a , if one or the other is a Z hole it provides even more reason to see the holes post dating the collapse of the sarsen .

3) Z2 and Z7 are new holes cutting into the earlier ramp meaning that they are later , no archaeologist having seen this evidence has suggested otherwise .
The Aubrey holes which predate the megalithic monument are not nearly as irregular the Y and Z holes , is it likely that the ability was lost prior to the setting up of the megaliths ? The Yand Z a holes being closer to the centre would also have been easier to scribe . Everything points to the reason for the holes being irregular is due to them being post the megalithic monumnet which got in the way . The other evidence supports this ,whilst there is nothing to support an earlier date for the holes .

It’s worth mentioning that David Field and Trevor Pearson in “Stonehenge Amesbury Survey Report pointed out that as Hawley did not provide decent co-ordinates some of the Y and Z positions in the north east are not quite right in the Cleal et al plans . However it doesn’t really change anything .
Just as a complete circle doesn’t follow the solar cycle ,the same can be said of the eastern arc as , it extends much further north than the solstice extreme .If it had some association with the solar cycle we might expect it to indicate the solstice but it blithely continues way past it .