I now have the same problem too.
Looking at it closely when it tries to eject I can see that there is a sort of mechanical latch in the front, center of the slot that closes the slot when the disc is spinning (maybe it's a kind of protection).
When I try to eject, the latch starts to move down but fails to completely get out of the way when the disc is pushed outside. So it happens that the disc bounces on this small latch and returns inside the drive again.
Then the latch is locked again once more and the disk is again mounted.
I successfully ejected the disc by helping the latch lowering during the eject process with a small plastic pick. I had to take particular care to synchronize my movement with the eject attempt from the drive.
So my conclusion is that either the mechanism that moves this small latch is worn to a point that it is unable to completely get out of the way at the right time, or it is bent somewhere and this prevents its correct movement.
Anybondy knows what I can do to fix it?
Apart from this the drive is working fine, is reading and writing everything correctly and that's why I'd rather keep it and fix this mechanical fault if possible.