I've had these euro style square headlights on my 1985 300D for a while now and they've always bugged me because when I try to adjust them, the knobs just won't turn. Something's binding. I'd like to get the headlights all adjusted right. It is the same on both lights. I've opened them up and tried to loosen the nuts on the adjusters but nothing seems to work. Did anyone else have this problem?

These are obviously not the Bosch european lights. They're Depo.

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1985 CA 300D Turbo , 213K mi