Thanks for the responses.
Well, now that you mention it, I agree. Chances of a well positioned plate are greater than of the opposite. However, I have been trying to improve the vibrating idle of this car (90k miles) during the last months. So far I have replaced filters (all), injectors/seals, engine and transmission mounts, broken idle air hoses, O2 sensor, spark plug wires, dist cap and rotor, and fixed vacuum leaks. With all this the idle improved, let's say 60% (engine startings, fuel economy and power too).

After studying CIS KE Jetronic, the sensor plate caught my attention and saw that the lateral position was displaced to one side of the cone walls. It was just a tiny deviation, but after I centered it with the central screw the idle improved, a lot.

Now the car is idling, let's say 90% well, and I realize that the engine behaviour is very sensitive to the plate position. Idle is smooth now, but it has yet this periodic small pulsation, so I wanted to be sure that the rest height of the plate is right.

Thank you, very much.
MMansilla