RABicle......time to do some normal, simple maintenance to your Cube. Here's what you do.
Get a few q-tips and a bottle of isopropyl rubbing alcohol. Whenever you have a "sticky button" problem, be it the console or controller, it's often caused by sweat in the case of a controller or grime in the case of the console shell. Either way the solution is the same.
For your eject and reset buttons: DON'T take the console apart. It voids warranties and there's no need to do it. Dip a q-tip in rubbing alcohol and swab the recess around the button with it. Let it sit a few seconds. Press the button a few times. Repeat. Still sticking? Take the blade of a thin knife and oh-so-GENTLY pry the button EQUALLY around it's outside. Repeat with the alcohol. After a few tries, depending on severity of gungy buildup, it should work.
New Cube owner? The correct way to remove a disc is to grab the outer edge with your thumb and third finger and, pressing the center hub with your index finger, lift the disc away. Small hands? Use the index finger of your other hand to press the hub.
Sounds dumb to mention it, I know, but like Shifty said....when the Cube was first launched I got more calls concerning that than anything.
"Thankyou for calling Nintendo. Have a great day!" (lol)