I got a really nice leather office chair for my house, but within a few weeks, it started squeaking when rocking. This has happened to me with all my other desk chairs with the rocking function. The squeak seems to be coming from the spring that allows the chair to rock (the one you tighten or loosen, depending on how you like it), but the spring is entirely covered by the plastic knob used to tighten it. Since it's covered, I can't really get to it with WD40, even when using that straw thing it comes with. I'm not overloading the chair, since I only weigh 170 lbs, so I'm not quite sure what to do about the squeak. Any suggestions?