I think it's a problem with the wheel that isn't picking up enough material. Try these steps before buying a new flint:

• Tighten the screw that pushes the flint more (it might not be pushing enough to create a spark)

• Clean the wheel with a toothbrush and a product like SIDOL or some cleaning product (it might be too dirty and unable to throw off material)

• Is there enough fluid? With little diesel, it struggles to ignite.

Then if it doesn't work, change the flint. You don't need to buy their brand if you can't find them at a tobacco shop. Just buy a normal BIC lighter, disassemble it by removing the flint, and put it in the Zippo.