Hub 13500 miles. Problem developed yesterday. In gears 10-11-12, varying, going up or down, gear inclined to finish up in neutral. If I backpedal, even slightly it slips into gear. Cables appeared a bit loose. Tightened them. No better. No resistance increase so I doubt that internal cable going (is original on). Oil replaced less than 1000 miles ago (a couple of months).
What should I do next?