...and, if all else fails, buy a new/some new ones. I can really recommend neodymium magnets....very strong for their size and remain strong (unlike ferrite, which weaken over time).
Huge choice on Amazon (and probably Ebay).
If you have an old computer disc lying around that you don't want, open it up and take the magnets out (a pair of kidney-shaped things on the edge of the platters). They are incredibly powerful magnets.