I will try cleaning the contacts.  I will also go through the Bentleys to
see which wire runs the tach and make sure it is making contact.  My fuel
gauge did not work for a while when I first got the van.  Turned out to be
this exact contact.  I did a great job troubleshooting it:  first I
dropped the gas tank and changed the transducer.  When it still did not
work I checked the wiring.

John