Borrow two straight pins from the missus. Get them with the little do dads on the end as they're easier to find when you drop them. Here we have yellow stars.
Open the butterflys and center one pin in the bottom of each opening. Close the butterflys and then adjust the center screw to where each butterfly has the same grip on each pin.
Done? return the pins and maybe she won't notice any grime that may have been transferred.