Before JetGuy told us not to use grease or oil on the graphite bearings, I was using grease and that did not cause any noises - just a sticky carriage. I put about 2 drops of 10w on those rods and that may have helped dissolve some grease that was still in the graphite bearings.
The z-axis screws run in bearings at the top and bottom. (I just removed my top bearings to eliminate any chance of an imperfectly straight screw from moving the build plate.) Anyway, could it be that a bearing has gone bad? I would suspect a bearing before a motor.
I would call TS on the phone to get some help. I have not heard of this problem before this. Please post your results here.
2 Raise3D N2 Duals, V2 nozzles, Bondtech BMGs, adjustable table, Panucatt SD2224 drivers, run-out sensor, thermal overload protection resistors on motion controller board, Firmware 1.1.8ABH - with Lin_Advance, Palette+