I posted some years back about reviving an old Apple with keyboard problems. I finally got the thing to stop going crazy when powered on (repeating garbage characters even with keyboard unplugged) by reseating chips!
However, I have two keyboards - one works fine but has some keys that are hard to press/register. The other one I want to fix does nothing at all. The light shines, and the reset button works, but none of the keys work, so I figured it had a blown MM5740AA/C. I found someone selling spare MM5740AA/E chips and bought a few thinking maybe they were compatible, but no luck- same issue.
1) Can the AA/E be used in place of an AA/C?
2) What else on the keyboard itself should I look for that would cause no keys to register?