There's no reason that a 1970s-vintage loco with sentimental value can't be made to perform as new.
I wouldn't spray the electrical cleaner in there indiscriminately. Put a little on a Q-tip to clean the wheels, the rotating copper commutator surface, and the brush wells- this should help performance. Disassembly is pretty straightforward, or you can search some YouTube videos of how it's done.
The wheel bearings might need a drop of oil, and the worm gear on the motor shaft might need fresh grease. If the old grease has hardened in place, you might need to dig it out carefully with a small screwdriver or toothpick.
The motor on this loco could take up to 2 amps so you should be running it with an AC transformer rated at least 25 watts, minimum. If the wheels and rollers are oxidized you'll see a lot of sparking at first, but as you run the train it should burnish off. If the rollers are heavily grooved, they might need to be replaced- an inexpensive maintenance task.
Good luck with your Coca-cola switcher!
