The Sony CMT-C7NT NetMD Mini System is one of Sony's nicest ones (IMHO). Even though it came out late in 2001, the compact design and mirrored finish along with the green light-up speakers made it a standout, even today! It's fully-featured including NetMD, Type-R, USB audio for computers, and more.
Since it uses an MDM7 MD mechanism that uses belts, it can fall prey to the belt stretching or losing elasticity.
Replacing the belt itself is not hard, but in a compact system like this, the hardest part is getting to the belt!
After getting inside the case, there are 3 layers (CD mechanism, middle tier board, and a metal box) to get through before getting to the MD mechanism itself.
I can't effectively write it up yet, so if you're interesting in fixing your own, or just seeing what I went through, please check out the video.