If you take the circuit board out of the can...you may see some loose solder joints that could be resoldered for an easy fix if that is the problem....A lot of these under dash enclosed circuits vibrate loose after 20 or so years.....especially the heavier components on the boards.....might be worth a shot to save some $$$....you can see the cracks on the solder side pads by pushing the components around gently....

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1978 Yellow 300D (The Mustard Toad)
1980 Blue 240D (The Iron Toad)
1989 Grey Mitsu.4WD Mighty Max Pickup (Needs a Diesel transplant bad)

(Open the pod bay doors HAL)