I have just started to notice a slight vibration when my lathe runs between 2000 and 2100 rpms. Up to 2000 and past 2100 it is dead steady, but within that range I can hear and feel the vibration. The lathe is not anchored to the floor and I haven' added extra ballast weight, but it hasn't displayed this issue for over the year I have owned it, until recently.
This happens with or without anything attached to the headstock spindle (drive spur, chuck etc) so I don't believe an accessory is causing it.
Nothing has changed with the lathe in a year, and it hasn't been moved or altered in any way. The ways are dead level in both directions so it isn't leaning at all.
I have tried repositioning it on the floor a bit, and tightened everything down I could get at, but these things didn't help.
If anyone has some ideas of what I can try to find and fix this I would be grateful.