My X1 has been fine with over 350 hrs of print time. But I noticed when I started my last print something is very wrong with the XY motion. Pretty sure it’s a motor failing but not a 100% sure if it’s motor A(right) or B(left). I do regular maintenance, belt adjustment/alignment, carbon rod cleaning, light lubricant for everything else. I tried different models thinking it was an issue with the g-code but no dice. I submitted a ticket but I’m wondering if anyone else has dealt with this.
Vid
Sounds just fine to me if it would be a cement mixer…
Try the very old hose trick 
Plug one ear and use a hose on the other.
Like this and if the hose is not too large in ID or too hard you can pinpoint the source of a noise really easy compared to trying with just your ears.
I use this when working on old car engines, washing machines and other things where it is hard or impossible to find the source of a noise or vibration.
Sometimes just a short length of PVC conduit pipe already does the trick, especially if wrapped with some soft fabric or fully stuff.
Could be dry bearing/rods, worn out parts OR just a matter of running the printer’s hardware calibration again.
The later especially if your problems started after a firmware update
I’m an idiot and didn’t notice that one of my presets had changed and had the acceleration set to 20,000 mm/s which is double the usual speed.
Hmm, not a certified expert here but something just ells me you fond the cause of the noise without tools 
Glad you did not start to take the printer apart to find this detail after…