Just dug this stunning machine out from its hiding place and I see the cable which links the cassette deck to the amp/tuner is missing.
I know it's a long shot but worth asking if anyone has one, perhaps from a set that was junked for parts.
It's the wide flat grey cable in the middle bottom of the photo.
It looks like the same cable is fitted to other similar models such as the XE520 etc.
Will pay postage etc from anywhere in the world.