Over time the wire coming from flywheel sensor gets dry and hard.The engineers should have allowed more slack in this wire.It runs up into the socket for the pins.When you try and screw on amp,the wire slips down.
My solution was to remove screws in socket,pull the wire out of socket holder.Clean everything good,and super glue gel the wire into socket.
Problem solved.

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1999 w140, quit voting to old, and to old to fight, a god damned veteran, deutschland deutschland uber alles uber alles in der welt