If & when my folders get funky, I wash 'em out by spraying WD-40 in there. Then, I blast 'em with compressed air (comes in a can, I have it here at the office for cleaning computer parts) to dry up the WD-40. Then, I apply a drop of synthetic lubricant. WD-40 is not a good lubricant, since it dries up leaving metal-on-metal. However, it does an excellent job as a cleaner. It is a penetrating fluid, so it's good for moving parts that are crusty, rusty or stuck, and it helps to expel any water from your knife's pivot. Make sure you apply some real lubricant afterwards (but not too much or it'll gather lint & crud, and you'll just have to clean it out again).