electric door locks keep chatters when locking

Could be a bad door lock actuator. Like all actuators, it's a small plastic box with plastic gears and a tiny electric motor and is prone to failure over time. You would have to remove the interior door panel to replace it, which can be tricky to get access to, however it is a cheap part, around $25-30.

Inside the door lock switch, between the Unlock and the Lock buttons, there is a spring-loaded centering pin. When it wears down or breaks for lack of lubrication, you can get the "haunted locks" effect. If you can identify which door lock does not center properly, it might be the culprit. It makes intermittent contact. There is also a feature, not a bug, that cycles the locks to warn you that you are trying to lock the doors with the key in the ignition and the engine is off. The lock is easy to replace ($20 online) but hooking up the metal rods inside the door is tedious. I use two wires to guide the rods into their attachment holes. I also sanded a broken plastic pin and stretched the spring to make up for the shortened pin.