Hi, remove the thermostat knob ( pull's off )then undo the thermostat nut. In front of the thermostat knob there is a green or grey plastic cap remove this cap then undo the screw, Slide the thermostat housing towards the rear of the fridge then pull it towards the centre of the fridge, This dislocates the housing from the cabinet. Remove the 2 screws on the rear evaporator plate to dislodge the capillary tube, Reassemble using a new thermostat and good luck. If you haven't purchased a new thermostat as yet you can do so at.
http://www.candmdomesticappliances.co.uk/product.php/1090/0/hotpoint-thermostat-261055
www.candmdomesticappliances.co.uk
paul, April 2009