I have three broken Xboxes with Samsung drives... Two of them are the same model, so I decided to switch the parts around and see if one would work.
Box 1... powers on, won't recognize discs... used to recognize CDs but not games, until I fiddled with it and worsened it. No dirty disc error, just blinks for a bit then stops.
Box 2... powers on, sometimes ejects disc instead of reading it, used to run games when manipulated to do so, but sometimes lagged a lot until it had to be restarted.
Box 3... I only took apart and put back together for practice before working on the others. It has a jammed tray, unlike the others which only have sticky trays.
The weird thing about Box 2 is it "UFOs" my discs sometimes... ejects them spinning and hovering. That was after doing a simple drive swap between the 2, before that it just ejected the disc instantly without reading.
After that, I decided to switch the lasers around... that actually made it worse, because now the UFO one no longer runs occasionally. I have no idea what to try now. The one that doesn't read seems like the most likely to be fixed, but I can't explain why changing the laser around did nothing whatsoever, if anything made it worse.
On the bright side, I just ordered 4 Halo Edition Xboxes in working condition... I'm thinking about selling these as broken, but would prefer to get my old one working again... it even has some nice game saves, like an early San Andreas save with most activities done and all outfits unlocked on Ninja Gaiden Black... plus some good Morrowind characters. Maybe I just need to get some memory cards to transfer those.