A method for rejuvenating a strand-blocked cable having a conductor comprised of a plurality of conductor strands with interstitial volume therebetween blocked by a PIB based strand-block mastic, the conductor being surrounded by a polymeric cable insulation. The method including pre-injection of compressed gas into the conductor strands of the cable at a pressure less than the elastic limit of the cable insulation, and injection of a rejuvenation fluid into the conductor strands of the cable at a pressure less than the elastic limit of the cable insulation.