Xbox doesn't recognize games, but 360 does

[Petrucci]

I recently bought a used Xbox off of ebay, and it came included with a few games (the seller listed Halo 2 and Pac-Man World 2, but they also left a copy of SSX Tricky inside). The thing is, the console (motherboard 1.1, Thomson drive) seems to not recognize either SSX or Pac-Man, but when I put them in my 360 it detected them, despite being unable to play them. I don't think the DVD drive on the Xbox is broken either, since it runs Halo and Halo 2 without a hitch.

Edit: I just played a bit more Halo 2, and it seems that cutscenes load strangely (e.g. textures, models, and lighting pop in)

 

[FAST6191]

That sounds like a dirty laser/laser on the way out, especially on a model that old.

You can try cleaning and then pot tweaks if you want. Depending upon how it got dirty then it might work, and pot tweaks are so much black magic at the best of times. Do clean the drive properly as well as you can also avoid the sticking issue.
If you are going to mod it via a game based exploit then do it sooner rather than later. Indeed I would probably see about doing it just to get the EEPROM/HDD keys.

 

[Petrucci]

Yeah, I have a copy of splinter cell coming in soon so I can start the modding process. I'd like to replace the drive, but replacements are either scarce or expensive.

UPDATE: I got SSX Tricky to boot. Originally, it wasn't recognized, then it only got to the XBOX logo, and after cleaning off the laser, it loads and plays. Pac-Man World 2 still doesn't want to load, though.