If your drive is going out, you can buy a new one from richspsxparts.com. I didn't wanna ditch my modded system, even after getting a PSOne and bootdisc, so I bought one and dropped it in. Worked like a charm.
One thing to bear in mind is that you want to look for the most reliable laser model. Rich's stocks most versions, but certain models are better than others. I know there were issues with some models being less able to read past scratches and durability. I could've gone with the same model I had (which was a good laser), but I decided to go with the PSOne laser model. If you go that route, you also have to buy a ribbon cable extension, as the ribbon on the laser is shorter.
All laser models are interchangeable between systems.