Did you try looking at Locktite 242. It's extremely pliable yet can handle constant vibration without cracking or loosening. Which are all desirable qualities when dealing with mobile products that have tendency to be banged around or even dropped.

Try re-installing the old OEM ram back in the unit. If this fixes the problem, then there is reason to suspect the RAM. But its been my experience that it's usually just a bad optical drive that will need replacement. They are known for going bad in several of the early Intel and G4 models as well.