yes hhkb spacebar stabilizer is a fiasco. On my type S it rattled everywhere. I opened it up, disassembled the stabilizer and put high viscosity lubricant everywhere where there would be surface contact. half put it back together out of the case and watched the stabilizer move up and down and studied where contact points would be and lubed everywhere.
Put back together and the stupid thing still rattled, not quite as bad though. However on my non type S there was no spacebar rattle. Only slightly when pressed on the left side which was no issue as I press with right thumb.