On my car when you remove the p/s lid, it kind of pops up due to the spring that is under it. The spring is about 3" tall. I used a clean phillips screw driver to raise the filter. It's easy to get it out. As far as the fluid level goes, the Haynes book (W123) says to fill it up to just below the lip. You're right about my Mitsubishi radio. Like I mentioned earlier they cut corners on the interior and such, but not under the hood.
The procedure for checking the fluid is with the eng. off after the fluid is warmed up, like after driving it.

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1999 MB SL500 (110,000 mi)
2004 Volvo V70 2.5T (220,000 mi)
2014 Tesla Model S 85 (136,000 mi)
MBCA member