I have the XSPC dualbay pump/res combo, so can't open it and check the pump etc as its sealed
And yeah like small threads :S Inside the cpu block theres like the grooves, a metal shield thing over it and within the middle of the metal shield thing theres a hole
Within the hole is where I found each of the grooves half full of the thread stuff
By thread I mean like, bits of frayed thread, tiny bits