I don't know if there is a 'fix' for this, but it would also depend on how worn/damaged yours are.
I changed these on my project 190, as the rubber had given up completely.
There are some cables available through Rimmer Bros for a very reasonable price, but may depend on the age of your car, not sure.
http://www.rimmerbros.co.uk/Item--i-ULS100140
http://www.rimmerbros.co.uk/Item--i-ULS100150