slot loading imac not recognizing int. cdrw

picked up a graphite imac real cheap
previous owner claimed to have fried the hd and said it booted to firmware prompt but couldn't get it to work
i got it out of firmware mode-ran command-v or whatever the command was and it cycled through the firmware screen and reset
i installed a hd i had laying around(pulled from a working imac) with osx on it
graphite starts up and runs fine
problem is it doesn't recognize the internal slot loading cdrw
what gives?
do i need to install a firmware update?
do i need to do something in the hardware settings for it to be recognized?
when i pull up system profiler-it's not listed in devices and volumes
i do hear it spin when i insert a cd in the slot though
any help would be greatly appreciated
thanks for reading

have you checked the connection, maybe the previous owner knocked it loose trying to work on the hd? Id find out the brand, and update the drives firmware.

I've seen two tray-loading models that have done this. In both the data electronics had died but the mechanical components still worked normally. The CDs would spin up but the lazers were not functional so the disks could not be read.