The spindle unit is not able rotate smoothly by hand after received in factory. During
disassembly, spindle out looking of moving keys have wearing mark from holder. Inside of
bearings have damaged at bottom side. As following figure, bearing retaining ring is
breaking. Spindle noise is coming from this part of abnormal working. After a period time of
running, bearing retaining ring is becoming weak and broken to make bearing heat up
abnormally running.