The poorly designed Gundlach fine focus mechanism, found in several different Bausch & Lomb microscopes of the late 19th through early 20th century is shown to the left. The use of leaf springs which could both wear and come loose was a major defect in the design; many of these mechanisms have broken or fallen apart over the years. The illustration is somewhat misleading as the springs were held in the center of slots, and there is no fastener. Not only can the leaf springs lose their recoil capacity with time, but they are held in place in the brass slots simply by friction. Brass is a relatively pliable metal so as the slits widen over time, the springs often simply come out.