In article ,
says...

I have this on my Bianchi Milano, works great, very easy to
shift. Not sure I would want to take one apart, looks complex.

For basic maintenance, it is pretty simple. You pull the insides out of
the shell. Then you can clean and lube the races. That's about all the
routine maintenance you can do. Anything else you send it back to shimano
to fix. Assembling the unit is also straight forward. At Interbike I played
with one and it was easy to work with.
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Alex