vaseline (or even baby oil) between the lead and the rubber casing to lubricate, try to run a fine probe around the entire lead so that there isn't any areas stuck together. also try to lubricate between the rubber mounting for the pins and the metal holder.
Once you have done that, try to force a blunt ended probe or rod between the lead and the rubber housing up to the pin mounting and then force the probe and lead through the housing and the pin mounting out of the its metal retainer.
