I have a one-handle "Marielle" model Pfister kitchen faucet diagrammed here. It leaked, so I replaced the cartridge, which solved the problem. A few weeks later, I happened to drain my hot water heater to get rid of sediment. Right after that, perhaps only coincidentally, my kitchen faucet output was reduced to a dribble, both hot and cold equally, even with the spout's aerator removed. Oddly, the hand spray still has plenty of pressure (hot and cold). All other faucets work fine. Disassembling the faucet, including taking apart the cartridge, which is clean, reveals nothing. The diverter valve (951-050 in the diagram) had a tiny chunk of sediment but removing that made no difference. Running wires through the faucet's connection legs finds no clogs or gunk. Disconnecting the incoming hot and cold lines and diverting them into a bucket reveals they have plenty of pressure. The pressure is dying after entering the faucet.
What's the cause of my problem? The cartridge? Diverter valve? Something else?