Premature tool wear, unexpected runout, or a sudden change in surface finish can make the spindle an obvious suspect. But before assuming the spindle itself is failing, it is worth checking something much simpler: where chips, swarf, fines, and coolant residue are accumulating inside the machine. Contamination at the spindle and toolholder interface can interfere with proper seating, while poor chip evacuation can cause chips to be recut instead of carried away from the cutting zone. Elsewhere in the machine, accumulated chips, sludge and contaminated coolant can turn