Yesterday we reported a problem with stiffness of the display hinge on some PowerBooks. On affected systems, opening the display produces no noises or untoward stiffness, but once the display is open, minor adjustments produce the creaking noises.
MacFixIt reader Nick Wirz reports that lubrication can safely be used if applied properly:
"Responding to Philip Chadwich's concerns about the aluminium PowerBook's hinges: Use a silicon spray at both sides (left and right). The same issue is with certain models of iBooks, Apple authorized service professionals are instructed to lubricate the hinges with silicone spray, so you might as well do it yourself. But I urge you to only use a silicone spray, use it sparsely and move the lid a couple of dozen times before lubricating some more (if necessary). The tension holding the display upright is controlled by a spring mechanism inside the hinge and will not be affected by your (sparse) lubrication."
However, make sure to only use a silicon spray, use it sparingly and only in the right locations.
MacFixIt reader Dorian Mattar used an unidentified lubricant and damaged a portion of his screen: "I have a G4 Titanium PowerBook and after 9 months the hinges broke I had them replaced and I got it back again with stiffness. I called Apple and the guy did said not to worry about it, that the hinges would not break again. I took his word and he did not file the call. Three months later I got hair line fractures I called and they said the warranty was over, six months later all the plastic around the hinges is broken and then next thing will be the hinges themselves. In between this time, I tried to lube the hinges and in the process I damaged the screen. I has some weird spots on the right hand side.