Is it specifically the adjustable ruler foot and did you buy it from a Bernina dealer? From the Bernina site it looks like it has a gold-colored knurled piece/disc to adjust the height.
In a Google search, in addition to that foot also I'm getting pics from eBay listings of a foot called a #72, but it isn't adjustable and doesn't have that gold piece. Might you have purchased the wrong #72 or possibly a knock-off?