Aux fan conundrum

[Fisherman]

Anyone ever experience this one?

After getting the AC back online I noticed that my aux fan is not engaging/running.

the car got up to 100 on the guage so I thought I'd check it out.
I opened the hood and then used the tried and true method of hitting the fan with my hand. You know that trick right?

Anyway, whenever I hit it the thing turns for a few seconds. So I kept slapping it and all of a sudden it starts to roar. Okay, I said, It just hasn't been on in a long time so that musta fixed it...

It didn't! Next time I started the car with the ac on I performed the same miraculous procedure and got it running again. My hand is a little sore now...

Now here is the conundrum. What I have found is that if I apply pressure to the outer edge of the fan hub the fan starts spinning. if I can hold a piece of metal up against it long enough (the friction makes things a little hot to hold) it seems to finally continue running on it's own. This means it is getting power I guess but what in the world is causing it to turn when I apply pressure to the hub? Could it be bad brushes?

I think someone the other day stated that they diassembled their fan and was able to replace the brushes but I can't seem to find the thread.

Anyone able to help or have thoughts on the why of the pressure on the hub thing and if it is brushes (?) as I suspect then please whoever it was that made the repair (Greg?) jump in here if you would.

Thanks