I suggest you get a Dremel tool and use a wire wheel to clean things up. Don't use the wire wheel on plastic. The wire wheel will make everything look much better.
When I use a wire wheel, I take a box about 10" square and hold it between my knees. Then I hold the Dremel tool vertically and work inside the box. The wire wheels will throw out pieces of wire as the wires fatigue and break off. They will get in you clothes and in your shoes and in the soles of your feet. The box catches them so they don't get you.
I don't think you need to disassemble the loco to lube it. You might need to disassemble it to clean it. If there is dried grease on the gears or shafts, 5W-20 oil will soften it. I am lazy about taking stuff apart to clean it. I do it only when it is absolutely necessary.