I have not tried Retr0Bright, so I can't comment on that but I can give a bit of advice on taking the 1084s apart. If you are handy with tools it is not too difficult to disassemble but care must be taken with the tube.
Once you have removed the back plastic shell be very careful not to let the tube drop down on it's neck of the tube. This will more often than not break the neck and render the tube useless.
Not trying to discourage you, just giving a heads up. I had a 1084s I was repairing and I accidentally let the tube slip back on to the neck and then there was no reason to proceed with the repair.
Regards,
AmigaEd