You could try to clean the lens with isopropyl alcohol or it may just need a tweak of the laser settings.
My CD32 wouldn't read anything when i dug it out of the loft (Not surprising after 15+ years of not being used), i tried cleaning it with no joy. I replaced the laser with a new KSS-210A (Sony) which i picked up off eBay for ~£10 using this guide: http://eab.abime.net/showthread.php?t=38904
. It's pretty straightforward to do so don't be afraid to have a go.
I had to tweak the settings a little as although it span up fine it still wouldn't read discs, I used this guide here and made small changes then tested after each tweak:-
After some patience it now reads all my original CD32 games with no problems at all. I can't get it to read burned copies though, i'm sure with a bit more tweaking i could get it working. Im happy its just working for now though and i can play all my classic games.