To isolate the switch as the problem, you can try jumpering the switch connector (female portion) as follows:

Jumper terminal 1 to 3 and 2 to 4. Then try 1 to 4 and 2 to 3. If that runs the window both ways, try cleaning the switch. If the window does not run, check terminal 4 for continuity to ground.

(Info is from the '82 Electrical Manual and assumes that '84 is the same.)

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