You will first need to slide the outer case off the inner insert, just as you would if you were going to refill the lighter fluid. Be careful when doing this, so as not to damage any components.
Now that you have the lighter apart, locate the flint tube/screw assembly. This should be located on the bottom of the lighter. Make sure that you have a small flathead screwdriver handy, or another tool that fits the slot in the screw head.
Remove the screw assembly from the insert and make sure that the spring and tube both pull free. Do not bend the spring, as this can damage the assembly.
Check to ensure that the old flint has been removed from the tube; if there is still a small remainder of flint, remove it from the tube now. Do not add new flint to the tube until all of the old flint has been removed.
Put the new flint into the tube. Make sure that you do not damage the flint, the tube or the spring (the spring should be off at this point) during this part of the process.
Now, gently replace the spring on the tube assembly, taking care not to bend the spring.
The entire screw/spring/tube assembly should be slid back into the inner insert now. Tighten the retaining screw firmly, but do not over tighten it. Over tightening the screw can lead to damage and might prevent removal in the future.
Now, replace the inner insert in the outer case. Check the lid operation on your lighter. If it does not close fully, you need to check the retaining screw on the flint assembly. Ensure that it is fully tightened.
You have now replaced the flint in your lighter and can once more use it to light your smokes. The process becomes second nature with just a bit of practice.
Brian is a consultant for an online specialty cigar lighter store and has expert knowledge of cigar accessories, including triple flame torch lighters.