Vortex Sound Research

I have an M Audio Axiom 49 and it has been in my basement for a few years. I stopped using it because I need to fix the USB jack. That should be an easy fix. But I noticed some keys I have to hit fairly hard for them to register and even then it plays a very soft note. I'm going to open it up soon and take a look but figured I would get any info beforehand incases someone else has fixed this problem before. I have never tried to fix a keyboard so I have no clue what I'm looking for that would cause this problem. I will say it is pretty dusty so maybe just a good cleaning will fix it.