Well, I took the plunge.
I figured that no one would disassemble their dvd drive just to show me, so I dived in, cut the white piece, and it's
nearly working right

I've tested originals and dvd-r's, and both boot fine if I push the drawer shut manually, but...........
if I close the tray using either the button on the drive itself, or the xbox button, when it spins up, it, for want of a better word, spazzes out, making very loud scary noises, before giving up and booting to dash, not reading the disk at all.
Can anyone think why? All the connections must be ok, so presumably its that damned white bit again.
Any ideas folks?
Any help greatly appreciated