You could try moving the brush plate 90°.
Although it almost looks that the brushes are not insulated from the plate?
Max.

 

You could try moving the brush plate 90°.
Although it almost looks that the brushes are not insulated from the plate?
Max.

Direct contact with the plate, I am thinking of after changing the bearings just resemble it and run it CW as I did run the motor hooked up to the compressor and it worked, the pump didn't blow up and I got compressed air, the only problem I see is that the pulley on the pump has fins that direct the air towards the pump in CCW motor rotation so while the pump works in CW the fins on the pulley will direct the air opposite of the pump

 

If it is a piston or diaphragm pump the direction should not matter.
If vane type, then it does.
Max.