I have this one, basicaly it's remarked Philips drive. Tomorrow i can open it and take pics where placed this plastic part.

Creative's 8x speed

Have too, CR-583-J, different model by Matsushita

That would be fantastic. It's so annoying as it has just slipped out from somewhere and I have no idea where.
Take care handling you own unit, but if your not messing with it like I was you should be OK.
Btw. I was fixing the corner screw post (visible in pic) and was just re-assembling when this bit fell out.
-Likewise I can't find any internal photos for the CR-583-J
Many thanks
D

I think I can see your unknown part at 1:11 in that video, in the upper right which is the underside of the tray mechanism.
From the text in your picture I can tell it's reversed horizontally and when your image is flipped the shape does pretty much match up.

Hope you can get the drive working again, mostly I find that re-seating and cleaning oxidation on flex cables makes the biggest difference 😀
Beyond that make sure the motor spins freely and spin it a few times by hand to clean the brushes /commutator if it's a regular DC motor. Make sure the sled and sled motor are moving freely - the Toshiba 2x and 4x laptop drives are especially bad for grease going hard in the sled motor which completely breaks drive functionality til that's freed up.

Thanks Thermalwrong. I think you're right. Apart from the much smaller switch moulding, the component you've spotted is the only other free moving piece of white plastic in the assembly. They match, so it's got to be it. You can also just see on the video how it hooks onto the rail on the underside of the drawer. The other side attaches to the sled and the sliding movement will depress the white switch component. I have been trying to put it into this position but it just wobbles out. Like the guy in the video I think I need to remove the PCB and ensure the position from the other side whilst re-inserting the drawer. -A job for tomorrow!

I bought this drive new in 1996 and it only worked for a week or so, so mechanically it's mostly very sound and like new. The problem was that the drawer failed to open or retract properly. I took it apart for the first time a little while ago and noticed that it ran fine without the metal housing, which didn't make sense. However the screw post was broken (since new, as I didn't do it!) and I noticed that a long crack ran from here through the front of the black plastic frame. This crack would flex open when the drawer moved, and since the drawer was not running straight it would jam somehow when the drive was reassembled. By the magic of super glue that crack is now fixed and hopefully, if I can put it together properly, it should be as good as new. I've applied silicone grease to the appropriate spots and the band is still OK, so fingers crossed!
Many thanks again for your suggestion.
D