Cleaning sticky residue off reverse of medals and plaque

[azyeoman]

I recently acquired a death plaque group that had had Velcro attached to the reverses of the medals and plaque in order to display them.  The dealer from whom I purchased the group removed the Velcro, but there is a sticky residue remaining and I would like to know what suggestions anyone has for removing it and not damaging the metal nor changing the original color, which is essential to me.  Thank you in advance for your kind assistance. John

Edited May 29, 2022 by azyeoman