Hmmm.. if it is much like the design of holders in my 2007 and 2011 MBPs, I am quite sure it is an Integral Part, and maybe a small bit of well-placed Silicone on each end of the RAM stick (avoiding the Electrical Contacts of course!!) would do the trick.. I hope..
I can not see a better 'fix' if as I picture the issue.. Good luck!!