This Winkhaus genuine gearbox - Split Spindle or Lever Lever. Winkhaus cases are held on to strips by pins. To remove the pins, tap them out with a punch (The centre pin must be accessed by undoing the screw on the case). Reattach by reusing the original pins.
Operation: Split spindle
Latch reversal: Push in latch and a screw will appear in back of lockcase. Undo the screw to remove the latch. Reverse, reinsert and replace screw.
Nightlatch reversal: The small rectangular slot adjacent to side of the spindle hole contains a black roll pin. Insert a flat bladed screwdriver and roll the pin to opposite side to reverse function.