the cavity wax is applied in the area that is under the wiper tray, this allows water/condensate to bead up and roll out of this area, if water stays stagnant or dries up here, it starts rusting. This wax was generously applied to this area when this car was built in 1977.
The wiper motor is open to the elements, when it rains water strikes it directly. To prevent the motor rusting/burning out mazda put it in plastic bag so that water does not enter it. To install a bag, you need to remove the motor from its first ball socket that connects the linkages, You then put a thick vinyl sheet baggie and make a hole with a hot iron so it doesnt tear later on. This exercise protects the car body and the wiper motor.
You may have noticed a dried out yellow coloured wax in the doors and some odd cavities in the car, This is the body cavity wax that was sprayed when the car was built. It is available but not in Pakistan as its not a "parchoon" type spare part like filters and spark plugs.
you will either need to make your own at home or get someone to ship a few cans to you.