10 The axle-and-link assembly is a key mechanism of the fuel metering. Over time, the pivot pin (center) can wear the holes in the counterweight arms into an oval shape. In extreme cases, such as the one pictured, this wear can permit the roller tip to move sideways far enough to completely clear the top of the spill valve. If this happens, the engine will not run. The jewelry-like axle-and-link assemblies made by Frank Antonicelli completely solve this wear problem.