not long time in country. Sorry.
With a sphere. Turn on hidden geometry. Select the whole spherE. center point is readily visible with hidden geomtery. Click with the move tool on said centre point and proceed as I explainde above.
If the center point of the sphere is on the wrong axis for your placement requirements, there are a number of ways to proceed but one way is to rotate the sphere from it's center point 90 degrees and then continue as above
