HI Fred,

Yeps, I've already done the job twice    

First for the Xevious    https://www.dragonslairfans.com/phpBB2/viewtopic.php?t=63

and for the Space Invaders Part II    https://www.dragonslairfans.com/phpBB2/viewtopic.php?t=124

Here's the procedure (from Xevious post):

Remove all the chips that you can like this, and don't forget to get a lot of pictures before removing them to avoid mistake when you'll replace them :



Hot water, soap & brush :



...don't be affraid...  



Check that procedure in that video right here : https://www.dragonslairfans.com/xevious/xeviouswater.avi

Carefully & slowly use the brush to remove solid dust between components (approx 4 or 5 minutes of work max) :



... and remove the soap with (hot) water like this :



Of course you've to dry the pcb before THE test     I'm using this  method to accelerate the process    :



Don't be affraid to clean pcb like that  

I'll soon start to work on a Pole Position II pcb... I'll take a longer video of the 'pcb cleaning' process if you want  

Good luck StarFighter (tm)