I had a similar problem with one, so I pulled it all apart trying to figure it out-after opening it up and not seeing anything wrong I put it back together again and it’s been working ever since, I don’t know what I did, but whatever it was its working well for the last year?? I bought the black box thing that it all plugs into thinking that had something to do with it (never used it)
the brushes are there once you take the
motor out of the housing