Hello , after sourcing a new 5th gear I have taken off the side casing and dropped as much oil from there as I could , could anyone tell me where the actual drain plug is and is it a square , torque or a socket , as I'm.persuming there's more oil left in the box . Also best way to refill ? I've read through the reverse light switch ? Is this the easiest way and finally I've read conflicting amounts on gear oil sp please if someone knows the right amount to top up I'd be grateful , its a mg5t gearbox , thanks again guys