Quoted from KenLayton:Depends on the manufacturer of the game. Data East/Sega/Stern Pinball use a shooter housing with a pressed-in metal bushing. Metal-to-metal contact needs periodic oiling with a couple of drops of oil.
This is correct. The material they use for the bush is called oilite. A clean and then a couple of drops of very ligh sewing machine oil will make it good as new.
Wax, grease or graphite powder will make it worse because it will clog the pores in the metal.