For lubricating the motor, I am Unable to open up the motor without breaking something or worried not able to put it back, so I didn't try. I opened up many motors before, but this one I cannot figure out how (without damaging it)
So I decided to clean it, and lubricate with wheel bearing grease from each end of the axle bearing area. I first use ~120PSI compressed air to blow it clean, then I connect the motor to power, and spend it. I use lower voltage to just get it to turn... maybe 60 or couple hundred rpm??
While turning, I apply wheel bearing grease to the end, while moving the motor facing up, so gravity pull the axle downward, exposing more for the grease to get inside.
For the other side, the Plastic blades are pressed in, so again, I don't want to risk damaging it, so I use a wire bended it into "J" shape, and put in some grease, and spin it... I keep repeating this and try to do it as much as possible. With power off, I try to spin the fan with my hand as fast as I can, and it does feel smoother each time I repeats it more times.
Then I remove the brushing, assuming it is never replaced, its over 200K already.
I did this twice, one from my previous sprinter, and I found this way is the easiest and best way to remove the clip that holding the spring and the brushings.
Just becareful, as they will crack and break.
I just ordered the cheapest one from ebay, $10 I think. it is longer, but its ok, I just cut them into right length, then file them into curve shape.
I wish I can provide more info on "Opening up the motor" but I doubt this motor even possible to be opened without permanent damage. if anyone did it before, please chime in. Thanks.
Incase you don't know how to take the motor out of the plastic housing, push into these 3 rubbers stopper, and the motor will pop/push/fall out.
Hope this helps guys!