Playstation 1 disc drive maintenance.

I just recently purchased a PlaystationSCPH-1001 from Goodwill for $23. My plan is to flash a GameShark as a soft mod device before I commit to soldering in the chip for a PS-IO. After playing a few games for a night or two with my wife it seems that the motor or spindle is not reading the disc as well now. I did attempt a swap method or two without too much success. I previously (when the PSX was new) installed a mod chip. So this soft-mod and swap method stuff is rather foreign to me.

In regard to disc drives and spindles, is there a solid way to know which is which? The drive seems to spin, but if the spindle is removed, there isn't much in the way of a metal bar latching onto a piece of plastic. I guess what I'm asking is if anyone has similar experience..?