To do this, first unscrew the wiring plug for the brake master cylinder fluid level warning sensor, then pump out the hydraulic fluid using an old battery hydrometer or carry out the affects by everting the car, removing the wheels and drawing the fluid off through the front bleed nipples. Then, remove the clutch brake master cylinder supply hose from the reservoir sideward and do not forget to cover it to avoid losing or getting the clutch fluid dirty. Locate the points where the brake pipe fittings are connected to the brake master cylinder, then remove the union bolt on the pipe, with the help of brake spanner, in case they are very tight, use penetrating oil. Remove the brake master cylinder securing nuts and take out the brake master cylinder out of the servo unit while preserving the O-ring for use later. If necessary, retreating the assembly by pulling the pin and removing the reservoir together with the two seals that can be fit in new during the process. If the brake master cylinder is bad, it is sent for replacement as there are no overhaul kits on this model. For refitting, clean the contact surfaces of the brake master cylinder and servo, in the case of the O-ring need to be replaced, put a new O-ring to the back of the brake master cylinder, appreciable with some force to tighten the nuts to the specified torque. Insert quite tight the brake pipes into the corresponding holes of the brake master cylinder, and then tighten the union nuts with an adequate engagement of the threads. Top off the levels in the reservoir with new brake fluid and bleed the brake hydraulics, maybe the clutch as well in some cases. Last but not the least, apply the brakes gently, and take the car back to normal road use.