The spreader spring is the small spring in illustration #2 of the link that Nuts posted. If that spring is a bit weak or bent inward the pads can rattle a bit. You can do one of two things, hit the lbs and see if they have a new one, or remove the pads and spring and GENTLY spread the spring out a bit. Then make the "Make the spring sandwich" as noted in the instructions and re-install the pads. That should solve your problem. If spreading the spring doesn't solve the problem you'll need to get a new one. The springs are very lightly heat treated so they are springy, obviously. But occasionally you'll find one that missed heat treat and is to soft. Anyway, when bending the spring do NOT bend the legs, rather bend at the fold at the top of the spring. Just don't get carried away and bend to much.