At first I thought it was just an inductor, but it looks like a specific transformer, while googling the part.no I came across a similar part on an old Sony floppy drive with schematic, eventually I was able to find the 400K schematic with the same part, these drives were used in old Apricots in the mid-80s. Unfortunately both sources are rare ,
If you dont have any luck finding one, you could try randomly replacing a part with a modern isolation transformer. , just leave pin centre pin disconnected on the one side. I dont know the values of these things or winding ratio but there is a good chance its just isolation and 1:1.