PS2 Disc Reading Issue

I have a phat PS2 that reads all PS2 games fine. They boot up right away. But with PS1 games, some games load right away after the PS2 start screen. While others do not and you have to click into browser and wait for it to read the disc, 2-3 mins, then the disc shows, you press to run and the game works fine.

So I opened up the PS2 to expose the disc drive so I could see what's happening. On the PS1 discs that don't load right away, it looks like it tried to spin the disc but doesn't get going. On the PS1 discs that load right away, it goes to spinning the disc right away at full speed. I've noticed the PS1 games that don't load up right away seem to be the ones that are slightly heavier due to a thicker layer of game artwork on them.

Another test that I did was put one of the PS1 games that don't boot up right away in, and gave it a push boost spin with my finger and it takes off and loads the game right away. So it seems clear to me an issue with the motor taking off the slightly heavier discs right away. The strange thing is if you wait on those discs 2-3 mins, they will eventually spin up and work fine.

So what could be the deal here? Is there a capacitor responsible for getting the disc motor going or .. does the motor part need replaced. I cleaned it as good as I could and it doesn't seem to an issue with it being dirty or not well lubricated.