The rollers are aligned with the white plastic cylinder between them. Yes, the disk gets stuck because there is like a white lever that the disk pushes, that lever is connected to the barrier.
//https://drive.google.com/open?id=1XiUpF3yY-k7HeZfQVR0j9O1_hzcDH7z0//
‘Image of my lens mechanism and the lever I’m talking about’
When the disk is fully ejected, the end of the lever close to the gear gets far and the gear is no longer touching the lever, which I think is meant to be like that. but when I insert a disk, for some reason the disk touches the lever but not with enough strengh to get the other end with the gears so it can start closing the barrier and get the barrels down to start spin and read the disk. so it just gets stuck half way, the only way I have managed to make it start is to push down myself the disk while interting it so the barrier raises enough for the lever to reach the gear and finish the process.
I have noticed that if I push from the far side of the gear it is easier than pushing from the gear side.
It could be a worn out spring like you said, I think that something else needs to happen while inserting the disk, the lever I mentioned earlier feels like it gets stuck until the barrier raise at least a bit.
If you have any idea what the problem could be that would be great, with a video even better haha. Cheers