(Moderators please feel free to move this; I did not see a forum for hardware questions) So I managed to snag 5 Playstation 2 consoles and all of them work, but 2 work with some issues. The two that have issues seem to have trouble "gripping" a small collection of blue-bottom discs (i.e. CDROM games as opposed to DVD games). I know for a fact that it is a spindle gripping problem (all DVDs, music CDs, and a good portion of my blue CDROM games work, but not all of them whereas there are no issues on the other consoles). And I have found a few bits of advice for working around this (e.g. adding stronger magnet to the upper portion of the spindle or even putting tape on the non-reflective side). However, could one simply just replace the spindle motor component? A new replacement would presumably not have any deterioration of the rubber gripping "gasket" on the spindle, and a new spindle motor would presumably also address the weak magnetization issue as well. While there are a few suppliers of new spindle motor packages, I have not found a single website or video that suggests a spindle motor replacement would fix this issue. EDIT: Forgot to mention that the model is SCPH-39001
Clean the rubber ring on the spindle hub. Cd roms spin faster and thus slip more easily. Replacing the motor would work too.
Thank you for the reply. I have already tried cleaning the rubber ring on the spindle hub, but unfortunately there is still a lot of slippage. My guess is that the rubber has decayed considerably; further cleaning only seems to actually chemically peel layers off the rubber (as evidenced by q-tips turning black). I will see if replacing the spindle hub will help.
Are you sure you're using the correct disc hub with the PS2? There's at least three different kinds. The ones used on early units have a deeper hole for the bump in the center of the disc. SCPH-3900x should be using the later one (same as SCPH-5000x, even though the stepper motor for the spindle is slightly different). Another thing to keep in mind, CDs spin at a higher speed, it's possible to have problems with the spindle motor and it cause unbalance and such vibrations make noise or cause the laser to have difficulty focusing. In that case you would have music CDs play but games fail booting...
If I'm not mistaken, the problem of only a few slipping could probably be (if you're using the correct spindle hub, as brought up by @I_oliveira) the fact that the discs werent either manufactured properly, or they've been used so many times, but what I can only guess is happening is that the hole in the middle of the disc (if this isn't happening in other drives where you know the spindle is strong) is getting wider since the plastic on them is wearing down. That is my only guess at this point, but I feel that it could be a possibility, especially if this happens in other drives. But, if this isn't happening with other disk drives (like with old ps1 drives, they will do the same thing too), then this is the case of the spindle wearing down, so you will need to replace the drive with the correct model drive.