The rubbing alcohol has to be 90%, or use smiroff vodka that doesn't have a strong smell. Also, the alcohol and vodka are used to help the oil move up the rattan reeds. You can find this information on a RU-vid channel named Clean My Space. In the RU-vid search box put, DIY diffuser Clean My Space. I'm a subscriber to that channel and have saved a lot of money by following her DIY recipes.
If the sticks are already well used, I am not sure if they will work effectively anymore. It would affect the scent as well if it was already used from a different fragrance.