You have a K-Deck mechanism. If you put "Panasonic K-Deck" into Google you should find further service information.
However I can tell you that F03 means that it is locking up as it unloads. The cause of this is listed as Load motor or drive, timing, mode switch. The fact that you have operation of it for some time shows it might be the mode switch. If it does eject normally at all, before it starts playing up also would point to the mode switch. You might get away with a spray of Servisol Video 40 on the mode switch. If not take care to remove it, as it needs to be set up correctly or it will create tuns of problems. You should be able to get one from Currys Partmaster.
It might look like this: