The 5 Volt rail would appear to be the problem.
There is a link on the PCB to all the components that run on 5V.
I decided to open the link and provide a 5 volt supply from a separate PSU.
The drive then senses a disc and opens the cover on the floppy.
I no longer get the error codes but the drive does not load or save programmes or erase discs.
Trying to draw out part of the circuit but its very tiny and difficult to see.
I currently suspect that the 5 volt rail should only be turned on when some action is required.
Further investigations later today.
There is a strip of links on the PCB but nothing is linked, this may be correct or links could be missing.
A schematic must be out there somewhere.