The technique all-in all sounds pretty much ok. There's mention at the site about "clips", etc. inside the p/s unit.

On mine, you unscrew a large black plastic knob, remove, then the metal lid comes off. I then use a deep socket 10mm to remove a 10mm nut on top. With this off, a plastic piece and spring come off a rod. The filter can be removed using needle nose pliers. The fluid level indication marks are on the plastic piece.

Do be sure to remove the return hose and not the high pressure hose. I had to take the latter off once - it was leaking and had a heck of a time getting it reconnected. Didn't want to catch.

__________________
Mike Murrell
1991 300-SEL - Model 126
M103 - SOHC
"Fräulein"