Is Downgrade of Plextor PX-W1210TA possible!

[striders]

The followin information is from:

####://www.snumpy.com/~gamecopy/games/gcw_cd-backup.shtml

"Plextor PX-W1210TA [12x10x32x] - IDE
Use firmware 1.00, 1.01, 1.02 or 1.04 - Newer firmware will not work, downgrade if possible!"

I have only been able to go back to 1.05 anything older gives an error message and will not continue. Is there a way around this, does any one know why it wont proceed, will it work with this version?