I’ve got a 98 Mountaineer that we use as a third car (backup). Wife’s complaining that the key locks refuse to work sometimes, leaving her locked out of the car. Do the microchips in the keys play any part in allowing the cylinder to turn to lock or unlock the door? If not, how does one repair or replace the lock cylinders?
The micro chips are for ignition only. Get lock graphite from the hardware store, apply small amount to key and see if you can lubricate the lock. That would be the first and cheapest way to start.