So what I did was altered the button code slightly to take the hole diameter from the first page and add 20% to it , if there was no Diameter it will set it to 8mm(4mm Travel in all directions) and pop up an information message advising of such.
The 20% should allow you to have the probe near to centre! If some one from NFS wants to contact me I'll send through the altered screenset and they can chuck, change or use it if they want.
And yes I have buggered a probe or two over the years TP, usually from not raising the Z axis after probing:-)