Right. They have one bad CMG with a good power supply, and one good CMG
with a bad power supply. Between them, they can get one CMG back and
running.

If I'm reading the articles right, they have multiple choices for
where to get a good power supply.

Four spare remote power control units are available on the station,
including one that is brand new.
http://spaceflightnow.com/station/exp9/040422gyro.html

That article also has a mention of some of the issues with the arm and
such.