Why is my ps3 struggling to pull discs in?

Lately, my Ps3 has been struggling to pull discs in, as every time I put one in, there's this kind of grainy sound, as if there were dust in the silicone lips of the disc slot.

If I'm not pushing the disc a little bit, the disc is either pulled in slowly, or not pulled in, as the motor is active. I've tried finding a schematic, so as to figure out where the disc retraction switch is, but I can't. And nobody seems to have this problem.