The airflow box and the old Throttle position sensor on typ914s is a carbon
track with a known resistivity per unit area.  The wiper will eventually 
wear a groove in the track and then wear through the track to cause some
degree of open circuit vs position.

Open the airflow box and reposition the wiper to a new "track" region.

Yep, it's a delicate little critter and yep you have to be careful.

Now if it's just a grunge situation, a bit of electrical contact cleaner
sprayed into the box whilst you move the vane manually will cure a host of
problems.
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         ___  / __   __/   ____/         Al Knoll HP Performance Technology /
        /    /      /     /             Center    Roseville, CA, USA 95747 /
       _____/      /     /             916.785.9453    (Telnet 785-9453)  /
      /           /     /             email:  alf@hpptc38.rose.hp.com    /
   __/         __/   ______/         ___________________________________/