The fact that a light cleaning improved the video problem suggests damage from a leaky capacitor. Try the RAM swap but, I'm almost certain a thorough cleaning in a dishwasher will solve the problem if there is no permanent damage to a trace or a chip. Search "dishwasher" to see how many people have actually done this bizarre method.

As for the sound issue, that definitely clears things up. The problem is on the logicboard and is almost certainly the result of a leaky cap. I've never heard of this problem caused by any other thing. Doesn't mean it can't be. Closely investigate the sound circuitry and thoroughly clean the board around them. If spot cleaning doesn't help, you've got another candidate for the dishwasher. If the dishwasher fails in both cases, you've got damage to the board traces or physical components.

The fact that the evidence points to leaky caps in both cases, means even if cleaning the boards fixes your problem it is temporary at best. The caps must be replaced.