I'm checking out a used clamshell ibook, (machine ID 406, is this a Rev A model?). It has been unused for awhile, sitting.

It will only run when plugged in. The icon on the menu bar does not show that it is charging. When I unplug it while running, it immediately dies. It will not retain the date and time.

Other postings here would tend to indicate the battery is dead. Would the CMOS battery also be bad? Or will it recharge if the ibook is left plugged in and running for XX hours?

How difficult are either of these to replace? I'm pretty handy (sort of ) with my Torx 8 screwdriver (replaced the sound card in a Wallstreet)?

Yes this is indeed a bad battery there is no onboard battery for the clamshell models! New batteries are about $76 CAN BE Found cheaper on e-bay or somthing like that