Chance has just put a couple of photos of an axe from the Keiller Collection which may have once graced/grazed the pollisoir stone....
http://www.themodernantiquarian.com/site/1973/polisher.html
and there is also other evidence in his fieldnotes for other stones being reused along the Avenue and the Outer circle; that is of course if they are being 'read' correctly by the archaeologist...
http://www.themodernantiquarian.com/site/10827/standing_stone_with_axe_grinding_marks.html