STEP
Remove 10mm bolt at top of reservoir (shown in green) and 10mm nut lower down.
Pull reservoir up as far as possible, and pull the disconnected pipe forwards
Connect a second, smaller diameter pipe into the open 'drain' pipe. The opening is about 8mm diameter. (I used the end of a small funnel for a good fit) Pipe needs to be about 1metre long. Put end into drain can, or other suitable receptacle
Top up reservoir with new fluid
One person has to start the engine to activate the pump, while another checks level in reservoir, and top up when it drops. This happens quickly, so take care to swich engine off and on carefully
Repeat operation until fluid drains clean
Reconnect everything, using a new jubilee clip on the removed pipe