Space Invaders Part 2 Help Needed - Garbage On Screen

Archived from groups: rec.games.video.arcade.collecting (More info?)

Hi all
Some help / advice needed, just got a really nice (will be after a good
clean) Space Invaders Part 2 Colour Cocktail, unmessed cabinet, etc BUT
the screen is just showing garbage, I reseated all the chips but still
nothing, the guy said it worked until he moved it then it stopped, I
bought it as non-working so I'm not worried but is there any specific
areas I should look at? Or if not is there anyone in the UK who is good
at fixing these
Its showing bands of colour with a real jumble of blocks and black gaps
on it, I've heard it may e the slam switch???
Cheers
Shaun