Please take this with a grain of salt, and this is my first post here, but these X2 mini-mills are a real POS, IMO. I have had a real love/hate relationship with mine, but I had bought it used, and did a full tear down and rebuild of it. This is half the battle, getting the table pulled off, all the cosmoline cleaned up, the ways cleaned, etc...this helps these little mini-mills a lot, IMO.
The one thing I wish I had done sooner, which I just did recently, was to add the belt drive. I really feel this could be one of the better mods for these little mills. For these mills, that plastic gear is a real weak point, and what causes a lot of the vibration/noise, IMO.
A couple ideas I can offer, if you haven't seen the *Swarf Rat video on the x2 mini-mill, Teardown, Tuning, and Tramming, you might consider it. I thought it was really helpful to get mine calibrated. As far as getting the table off, understanding how to disassemble the mini-mill, that video is invaluable. It also discusses how you can adjust the spindle bolts to try and reduce the noise. But honestly, these are just a POS with that plastic gear, do yourself a favor and get rid of it. I would get vibration on mine at specific speeds. The belt kit will allow it to go much higher rpm also.
I also replaced my torsion arm with the air shock, it is also not without problems for me. But my little mini-mill continues to function, oddly enough and as much of a POS it is, it works. Do yourself a favor and get the belt drive, you will be happy with it. It makes these little mills much more usable. I am considering turning mine into a cnc possibly, and I would have never given that a thought before adding the belt drive kit.
The more I go along, the more I replace on my mini-mill. It is getting to be a usable machine. Most of my machines are vintage, and this is about the only one that could be cnc'd.
Again, consider that belt kit. My $0.02.
[* no relation to LittleMachineShop, just a satisfied customer]