I hooked the G4 to the Mac Pro running 10.9 via FW; I booted the G4 holding the T key a number of times, no chime, then after a number of reboots, the chime sounds, computer fan running, but nothing shows on the Mac Pro desktop--no disk icon of the G4.
I shut it down, on another reboot, the chime sounded, and I noticed that there was a flashing light from the Waacom tablet that I'm using for its mouse . . . then suddenly the computer "quit" or "died." Thought it was the final hurrah, but on reboot computer started, but back to the no chime.
I was thinking that somehow the previous scenario was showing intermittent power through the usb ports, as the potential problem; or somehow the Waacom tablet was pulling too much juice through the keyboard (even though the cable is a 1/4 inch thick).
So, this am, I tried about 20 starts using various methods of plugging the tablet into its own usb port . . . no chime . . . no power appeared to get to the tablet's light today. And, then, I tried the only other keyboard that I have, the new-ish Apple keyboard usb plug-in, which I couldn't remember if the G4 "couldn't read it" . . . possibly the case . . . anyway, I plugged that in and rebooted . . . no chime.
So, possibly the only other thing I could try would be to plug the MBPro running 10.6 to the G4 FW and try the boot sequence with the T key and see if the G4 shows up on the MBPro desktop. Or, I'll be ordering the adaptor thingie in a few days, and pop the HD when it gets here? I was thinking that there was some indication that the usb port card was faulty, but, I can boot the computer using the keyboard power button, but not shut it down . . . but, otherwise, nothing consistent enough to "prove" usb port as "failed" . . . and still didn't plug the display back in; also was thinking that the chime didn't happen when the display was plugged in, but, when unplugged, intermittent chiming . . . there again, nothing consistent enough to show video card . . . .
I'll be back with the latest development(s) . . . whenever that might be . . . spent the night thinking that moving the Waacom tablet plug to its own usb port would "solve" the problem . . . no dice.
edit: just saw yr post about copying the >var folder . . . I'll see when and if I can get it into a readable T mode.]