Answer to "Why won't the laser move back to the center of the disc?"You need to adjust the variable resistor for the laser power. I only tweaked mine a TINY bit. You don't want to send too much current to the laser. Just tweak a tiny bit, test, repeat if necessary. Here's a nice video: https://www.youtube.com/watch?v=0pQRKbxK... Has anyone noticed the black gunk (assuming it's dried motor oil/lubricant) worm drive gear? I've seen a couple with this issue, although not a deal breaker I'm thinking it will extend the life and possibly quiet it (a little). I suppose I could get some real lubricant, though I was thinking motor oil from the garage. Would that work? Update: Also, how do you guys clean the shafts? Rubbing alcohol or just wipe them down?