Fuel gauge sender unit - how to remove?

I have a South African 1992 Uno 1100. The fuel gauge readings have become erratic and I am convinced the problem is with the sender unit in the tank. I am not sure how to remove the unit. The manual states that it must be unscrewed. The unit is white plastic / nylon. On opposite sides there are two lugs which may be for intended for a large fork / special tool. I have tapped on these lugs to try and make the unit turn but obviously I don't want to bash away at them and break the plastic. Any advice?