You can buy hydraulic oilers to force oil down the cable. Not the cleanest job but I’ve had success in the past if you’re on a budget.
HYDRAULIC MOTORCYCLE / MOTORBIKE / QUAD / CAR CABLE OILER, PROFESIONAL QUALITY https://www.amazon.co.uk/dp/B006GGNVLW/r...xBb0E7F684
HYDRAULIC MOTORCYCLE / MOTORBIKE / QUAD / CAR CABLE OILER, PROFESIONAL QUALITY https://www.amazon.co.uk/dp/B006GGNVLW/r...xBb0E7F684