'86 420 SEL Cruise Control
 

Hi; I assumed my car's cruise did not work;I tried it last week, and surprise! holding the lever toward the "accelerate-set" position will cause the car to accelerate, but the control will not set and hold the speed; it will accelerate until the lever is released, at which time the car stops accelerating and the cruise disengages completely.
I thought this might simplify the diagnosis; better than "my cruise doesn't work; what's wrong?" Any suggestions?

RE: '86 420 SEL Cruise Control
 

wiring, loose contacts.