W124 Power steering fluid leak

[punjabi]

My W124 300TE Auto 12V has a PS fluid leak from the pump vicinity (pipework in/out from the pump) but the steering is fine like normal.
1. What could be causing the leak - the pump or the Hose joints?
2. How do you check the fluid level - the pump seems to have a sealed metal cylinder with a small black hex shaped plastic plug on top!?! Is this meant to be opened up to check or top-up fluid?

 

[grober]

They all leak to an extent usually out of the pulley spindle seal. If the level is OK nothing to worry about. Unscrew the black hex plastic knob [ anticlockwise] it will lift off. You will then see the end of a threaded stud protruding through the circular lid. Lift it off to see the fluid level- there's a plastic sleeve with the hot and cold levels marked on it. Top it up as necessary- get the fluid from MB.