Tried most of the above suggestions tightening the mounting screws,the fan does have rubber washers betwixt itself and the case,,the case itself is not that spectacular, about the same size as a VCR made of pressed thin metal which does not help,will tell the chap to see if he lay his hands on a better quality fan,trouble is it's a tad smaller than the modern CPU fans more like the one's from a puter ten years ago and the possible spaces to fit it are limited.
Anyway thanks for the help chaps.
