1.replacing wick once section of wick is gone......DON'T
the wick in a zipo is about 4inches long.so once you think you need a new wick,pull at it gently with some needle nose pliers.the wick should advance.pull it to about the height of the chimney(refer PARTS OF A ZIPPO .) and cut the wick where the fresh wick starts
2.replacing a flint because it a milimeter shorter than standard size......DON'T
just because the flint is a little shorter than a new flint DOES NOT mean you have to replace it.
3.replacing the rayon balls in the bottom with cotton balls.......DO
if you lose a rayon ball,is it definitly ok to replace them with cotton balls,just go a little slower when refilling