Now I still haven't found the way to bring the blacks back
to where they started, but I provide you with the info you need to prevent your S1, S10, GW10, G10, G15 and V10 to ever be plagued with the black level bug - that's for the G12 Plasmas that haven't reached the magical border yet.
One warning: The following procedure has been tested with several german GW10 and S10 so far! The specific way could
be different to US-Models, but since the EEPROM of all G12-models is very close to one another, I doubt it.
Okay, we have to go into the servicemenu. Once you are there, got to the page with the SRV-Tool. Click "Ok" and the SRV-Tool will open.
Since you are users of this thread, you will probably know this SRV-Tool already.
If you went with the cursor down, mark the last field on the right hand and press the Mute-Button for more then five seconds, your amount of hours, that the display was used will be displayed along with the number of times, you powered it on.
Okay, what we do now ist to mark the first field from above on the right hand instead. Again hold down the Mute-Button for more then 5 seconds. An option called "Memory Editor" appears.
You click "Ok" aka the actionbutton at your remotecontrol and voila, here is the heart of your TV, the EEPROM.
"EEPROM Peaks" is our next station. Mark it with the cursor and press "OK". You can navigate with the cursorbuttons of your remotecontrol and move with the channelcontrol up and down through the bunch of pages.
The lines of interest, which contain the internal clock
are 6C8 and 6D0!
They can look like the following for example:
6C8: FF FF FF 52
00 00 1E 29
00 00 00 FF FF 00 00
The fourth hexadecimal letter of line 6C8 represents the number of times, your TV were powered on. 52 means 82 times!
The seventh letter of line 6C8 are the minutes and the last letter same line represents the hours the display has been in use. 1E is 30 Minutes and 29 is 41 hours.
The first letter of line 6D0 makes the hours complete. In our case, it says "02", which means, the mark of 255 hours has been exceeded two times.
This means 256 hours * 2 + 41hours + 30 Minutes-> This panel has been used for 553 hours and 30 minutes!
What we do now? We mark all four letters each and reset them with our volumecontrol to zero! Save each entry to the EEPROM with the Action-Button (aka "OK") on your remote control.
After your changes, press "Exit" two times. You are back in the SRV-Tool. Now press the "Exit"-Button for more then 10 seconds and your TV will restart.
You now have a TV, that has been powered on only one time and has zero hours of use on its shoulders.
Repeat this regulary and the Black level Bug will never touch you.
Another possibility is to set the clock of a new G12 plasma to let's say four thousand hours, since the three voltagebumpmarks should never kick in. This would spare you the need to reset the clock again and again.