I tried the Yrr tweak last night but unfortunately my set was at it's limit already and only the tiniest of turns resulted in misfiring pixels, but the annoying thing is that the misfires were only on the top half of the screen and turning the Yrr pot a bit more resulted in the bottom half getting lovely and black and the top half misfiring with a clear horizontal line separating the two halfs!
Top half was dark grey and the bottom half was getting darker (Black). I had to put the pot back to where it was so my black level is still poor but I could see how low it could go but only on the bottom half
I didn't check the voltages against the sticker as I am waiting for a new multimeter to be delivered but the fact that the misfires happened immediately after turning the Yrr pot suggest that my voltages are out or too low?
A picture of what I see before and after tweak (In paint LOL)