no high beams

I just installed a set of used Bosch euro headlights on my 1988 420sel. They look great and low beams are fine, but the high beam and fog light do not work on the passenger side lamp. I switched bulbs between the two sides and the passenger side still doesn't work properly.
I sanded down the ground connection but to no avail. I'm out of ideas... any suggestions what I should do?

thanks
Peter
1988 420sel
1988 300e (sold)
1982 300sd (wrecked)