Sounds like the H7000 and the H7002 angular contact ceramic ball bearings had a deep scorch since the beginning of their assembly, happens to us on one of our production spindles, DAMN those bearings cost a lot!!! the china made will cost you $45-50 a piece, the japanese NSK version $100-120, but I ended up buying the NSK 6002 that only cost $1.90 a piece, took out the covers for a more freeflow motion, washed it with gasoline to take out the internal lubrication, put some high temperature grease, now it runs so much smoother using the original NSK japan ball bearings with a fraction of the cost. haha
You can inspect the ball bearings by opening the tiny allen bolt on the inner shaft side, it`s a spring loaded (6 springs) after taking out the screws you can safely pull the motor shaft directly to inspect the bearings.