Original started squeaking and binding about a year in. Tried external wd-40 lubrication w/o success, lived with for several month, then after researching online found Delta would replace under warranty. New cartridge arrived in a week as promised (great customer service!), but came dis-assembled (?) w/o any schematics. Fortunately a good youtube video showed breakdown/assembly. Installation easy.
Inspecting the old unit I found a small chip on the edge of the white ceramic disc which probably created the problem, so disassembly and re-lubrication with silicone grease would not have helped. Hopefully materials and manufacturing of the cartridge have improved so that it does last for the million uses that Delta advertises. Had forgotten how smoothly faucet operates when working properly!