I'm on my 3rd motor / fan replacement. Firt one got crickets, second one quit entirely until I took it out and wacked it with a block of wood, then it started working again but I sent it back and got a new one. They are real easy to deal with and obviously make a tom on the units because they replace them and pay the shipping both ways, every time...
I don't believe it's the bearings, I believe it's the brush assemblies, that is a brush type motor. The motor case is welded shut so no getting inside though I may grind off the welds next time and dissect it anyway.
It's a Chinese motor btw.
