if you have the manpower to take it apart then do so, it will make getting it upstairs so much easier
Carefully. That's just light enough for two guys to carry and just heavy enough to hurt the guy on the bottom pretty badly should it get out of control on the stairs.I think two guys could easily carry it upstairs for you.
The outside door is 12' past the stirs doorJust a quick note. If straddling the door with a 4x4 or whatever to winch it up the stairs. You will still need help getting it through the door as it will stop at the top of the stairs.
I looked up the specs, says the machine weighs 190 lbs. so not too heavy. I think two guys could easily carry it upstairs for you. Like RJ said "A six pack or two is a wonderful tool for moving heavy or awkward machinery"
If you do end up winching it up the stairs, add a strong rope with a ratchet prusik as a safety.
https://en.wikipedia.org/wiki/Prusik
The prusik can easily be slid up the rope as you move the lathe. If something goes wrong, the prusik will grip the rope and prevent the lathe from sliding back down. Another advantage is that the rope and prusik can hold the weight if you need to re-extend the come-along for a second move, since the come-along cable may be too short for the length of the stairs.