Your Forks may be leaking due to the hard chrome having corrosion pits or worn through and scoring on the tubes. Any of these will cause your seals to fail.
This requires your forks to be disassembled completely and in some applications, the feet to be removed from the tubes. The tubes will be sent off to be re-chromed. The tubes will be ground back to bare metal, built up with fresh hard chrome and them ground to tolerance.
Please be aware the above process may need to occur a number of times if the grinders find air bubbles and therefore, this may take quite a few weeks before completed.