maybe there are corroded contacts, or it has just worn out.
But I'm not a tech. Have you checked the price through the partsshop/fastlane stores on this site?
'92 300CE - Sold
2004 C240 - C7 Wheels
2015 ML350 - P1, Pano, Ash poplar wood, Sport Dinamica interior, Running Boards Keyless go.