My memory from a 562b that I think is similar was that the read head cage should be down and then the tray just slides in from the front and it should engage with the cogs so you can then just push it back, with the read head lifting up just as the tray closes. I don't remember having to be careful lining anything up. There was a small catch at the back of the tray that stops the tray from pulling out, and you have to push past that when putting the tray in, but that's at the very start. If you want I can do some dismantling over the weekend and double check.

Thanks a lot. No dismanteling needed! I found the problem - for some reason the drive motor had stopped working the very moment when I was putting the tray back in (leading me to the assumption that this was the cause for the drive no longer working). At this point I panicked because the machine Im putting together relies on the SB + CD interface combo. However, the tray is put back in exactly how you described it. I was able to free up the motor again and now everything works. I hope the motor will keep working but it is of course its 20 + years old - fingers crossed. Thanks again for your generous offer.