Stepdown ferrule may be the answer, if there's nothing stopping the end of the cable over time the metal inside the outer can work its way out of the sheath.
Have you try blowing through with a air line ? maybe only the inner cables goes through the middle off the top tube and outer is only at the front and the exit..my guess
Stepdown ferrule may be the answer, if there's nothing stopping the end of the cable over time the metal inside the outer can work its way out of the sheath.