No green light on Stannah 260 Stairlift (curved)?

My mother has a Stannah 260 and the green light on the arm is not coming on with the key switch, main switch below the seat and switch on the arm set to ON.
I've checked the 12v 7AH batteries and replaced one of them due to low voltage.Wiring is correct. When the switch below the seat is set to ON the charging light goes out but no green light or movement of chair. All sensor switches are clicked OUT (not pushed in). Chair is at bottom of rail in charging position. Charger is working correctly, giving 24v plus. Batteries fully charged. Line fuse OK and circuit board white fuse OK too.
Any ideas please? or contact for repair giving price for initial diagnosis? I live in Leeds UK.