Toyota Repair: instrument panel, automatic door locks, toyota corolla

Question
i have had previous answers from u pertaining to this car where u told me to change the speedo sensor because it is causin the check light to come on which i did and that solved the problem and the car is a 1993 toyota corolla LX limited 1500cc now i have noticed that the speedometer is not working neither is the tachometer i know the sensor is workin because the trip and the odometer are registering  and the automatic door locks are working (i.e they lock all the doors when the car reaches a certain speed) i wanna know if the motor that controls the tachometer and the speedometer are replacable and why they arent working ?????

Answer
If the other gauges are workingthen the instrument cluster may have a problem, all the gauges receive voltage through the gauge fuse, there may be a bad ground connection at the back of the cluster on the circuit board or the circuit bord may have an open circuit.