Halfords sell a Bikehut oil thats got Teflon in it. Using a syringe with the hypo needle you can inject it directly into each cable at the servo. Needs a couple of goes & some just floods back but as soon as you put enough in past the highest point, gravity is on your side & it siphons down in a day or so, even quicker with heat from the engine. Did the same with the clutch cable, really works well.