I think I may have the Z-Axis stepper removal figured out;
1. Jog the bed up to near top height and power off the machine.
2. Prop up the bed so it doesn't drop down. I used a paper towel tube.
3. Loosen the four hex nut set screws in the linking collar at the bottom of the threaded shaft. (They're really small, place in a safe spot.)
4. Hand-turn the shaft high enough to give some clearance to the top of the stepper.
5. Remove the stepper and separate from the mount.
6. Install the dampener and reinstall the stepper.
7. Hand-turn the shaft back down and align with the top of the stepper motor shaft.
8. Replace the linking collar, replace and retighten the hex nut set screws. Remove the item holding the bed up to height.
9. Test the bed for free movement by jogging down.
10. Power on and calibrate.
How's that look?
Edit: ...and this is exactly how I did it today
Win 8.1
Improved Da Vinci 1.0 with Firmware 1.2.5 and stock extruder
Arduino cartridge resetter and after-market ABS filament
TinkerCAD, Netfabb, Simplify3D