hi there, i had the same issue with mine and i can say the problem is solved for me.
sorry, my english isn´t perfect but i try to tell you what i´ve done:
the creaking sound don´t come from the metal springs inside. it is the backplate in combination with the pentalobe screws (in english clamping?). i´ve bought the i fixit 54 bit driver kit including the pentalobe screwdriver size 5. i just take out the screws from the backplate (i don´t take the plate off) and screw them in again. i´ve tested around and now i know the 2 screws on the left and right middle from the plate are the "bad" ones. i put them in too but not so tight than the others (half rotation left).
now there is nothing ceraking anymore! really nothing!
maybe this is the sollution for someone else.
regards
ps: what i´ve to say>before i try to fix it by myself i spoke to some guy @ the apple retail store in my city but he told me that there is no solution for that!? he can´t help me and i should call the apple support. when i called the apple support they told me i should go to the next apple retail store........... to do something by my own is sometimes the best isn´t it? :-)