Might want to just pull the brush /Reg Assy....clean the contact areas and reinstall....My brother an E.R. Doctor from N.O.L.A. says..... taking something apart and putting it back together fixes it 90 percent of the time...and if you take it apart enough times ...eventually you will have enough parts left over to build two of them......

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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)