Remove the flint if you do use the lighter. Flints deteriorate after time and can freeze the flint wheel.
If you have a flint that has deteriorated and need to remove a blockage use a thick wire or a metal pick to remove the blockage. It can take a while and do not use force. Once the blockage is removed use a pipe cleaner to finish cleaning the tube.
Use WD-40 and remove jammed inserts and to clean the case. Use pliers with a hard rubber covers to remove inserts. This will prevent scrapes.
To remove carbon use a popsicle stick to loosen the carbon then a Q-Tip to clean the debris. The wood popsicle stick prevents scratches.