X-CM31 not reading CDs all the way?

I recently bought an X-CM31 second hand, and it works just fine except that when I put in one of my CDs (CD-Rs with mp3s burned on them, they work on my discman) it only reads 5-8 tracks while I know that there's 30+. It also stops playing after 5-8 tracks. I googled it and the general consensus was to clean the lens/laser but when I took off the casing I found the CD drive was covered by a circuit board which I don't wanna fuck with.

What should I do? I'd like to avoid getting it serviced as that can be really expensive. I'm really new to this stuff, explain in simple terms please!