I have a set of these and they really are awesome and so simple to maintain.
Marzocchi manuals can be difficult to read however.
Basically you need to release the air, remove the top caps, drain the oil, unscrew the bolts on the bottom of the legs and it all comes apart.
Be careful with the seals, wipe them and don't get any dirt on them and lube them with some fork grease, I use Manitou Prep M and it works fine.
Fit the stanchions back into legs and screw together, can't remember oil quantities but it's up to just under the thread with the stanchions compressed.
Finally make sure you use the right oil / air pressure. I'm about 10.5 stone and use 7.5w oil and about 45psi and the're plush as anything.