Jigsaw blades can wear down and lose their cutting ability, and sometimes on a stubborn piece of wood or metal they can snap completely off the machine itself. Several newer Bosch models have a button to eject an old blade automatically and allow easy insertion of a new one, but older models still require some manual work. Replacing blades in these models is fairly easy with a few simple tools and know-how. The replacement blades themselves can be purchased at any home improvement store, but you should check the model number of your jigsaw beforehand to ensure that you buy the correct blade.
Looking down at the top of the unit, locate a small hole directly above the handle, directly in line to where the blade lies.
Insert your screwdriver into this hole and loosen the screw slightly. There is no need to remove the screw completely.
As you loosen, use your other hand to pull on the blade gently. When the screw is loose enough, the blade will pull out from the unit and can be discarded.
Slide the new blade into place facing the same direction as the old blade.
Holding the new blade in place with your free hand, tighten the screw all the way and remove the screwdriver.
Jiggle the blade slightly to make sure it is secure and does not move any inside the unit. If it is solidly in place, then the jigsaw is once again ready for use.