1998 GMC Sierra wipers, windshield & visibility problems

While driving in rainy weather for a long period of time at 50 MPH, the driver noticed smoke coming from the vents . The following day, the consumer took the truck to a licensed mechanic and was told the windshield wiper motor caught fire.

Intermittantly the windshield wipers become inoperable. Usually after they run a while and usually stop at the worst time right in the middle of a heavy downpour. When I open the hood I can hear a soft buzzing noise. When I wiggle the cable harness assembly that goes to the motor the wipers will start again. But then when I shut the hood the vibration sometimes causes the wipers to stop. This had been going on since last year, 2004.