Mac OS 9 - Flashing Question Mark

[Applal]

I too, have an iMac. This one a g3/400. I used SuperDuper to clone the drive to another Mac (in this case an iMacG5). I did this so that I could then replace the hard drive of the older iMac. I replaced the drive, jumper set to master, partitioned it, installed os9 drivers and then proceded to clone back. All seemed to go well. OSX started right up. Classic worked fine. All applications in x and 9 worked. Then I tried to boot from OS9, which this computer had no problem doing before. When I did, I too, got the flashing question mark over a floppy icon.
The system folder appears to be blessed.
I tried booting from a known good OS9 bootable CD succesfully.
I've tried just copying over from the disk image to the G3 using FwTarget DM. No change. I've tried 'reblessing' the system folder by moving out and back in the system and finder. No change. I've run TTPro4, all tests. No change.
I've re-reformatted the drive to a single partition (originally had 2).
No luck.
What could be the problem?