I just got my new switch from fastlane and installed it but there is still no response. I don't hear anything at all when I press down the switch. What else should I check? I also just got my service manual today. It's not straightfoward for finding solutions to problems. can anyone provide any navigation tips for it?

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W126 1983 300SD 286,000 miles and ticking
Baby blue exterior Grey MB tex
Recent work:
Replaced air cleaner mounting brackets and heat shields
Replaced alternator, fan and power steering belts
Replaced positive battery terminal
Replaced negative battery terminal and cord
New Duralast Battery

My car needs work.