Hey thanks all, I really love this forum. I changed regulator, delved deeper into this and looks like it is some kind of custom TIA, the writing is upside down and deff not a normal factory TIA chip. Anyhow, took it out cleaned all prongs and reseated it and still same all though at the minute not as bad. But still does flicker on a few games but nothing that kind of spoils the gameplay, for me anyway. Seems to be worse on PacMan and Dig Dug but them carts run perfect on my other systems, so I know it is now a fault with the carts. I deff now thinking it a TIA issue.
Not having the best of luck at minute so wouldnt suprise me lol. I bought a woody last week, everything looked kind of grotty inside and out, cleaned it all up and changed all the caps, everything running great for about a week! Then, all of a sudden half of the game sounds went, like somebody had turned a sound balance from centre to left or right, if that makes sense. Tried everything with it, then swapped the TIA to a known working one and everything was perfect again!
So now have two woodys 6 switch with two bad TIA chips! GUTTED lol.