My cursed TSDZ2...

[not dave]

EDIT
But no suitable attachments...
What attachment would be best to file back the face of the crank - something like these?

 

[vfr400]

The large cutting discs are best, then the rough sanding tubes. Those stones clog up straight away. I use a carbide burr, but it's difficult to get the right size shaft. Dremmel ones have the right shaft, but are expensive.

These sort of things. The Chinese ones have slightly smaller shafts so they slip in the chuck after a bit. I think it's the difference between 1/8" and 3mm

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[Bikes4two]

................... I, in my ignorance assumed that a crank was a crank, so have simply removed the old one and refitted the new assuming things would be fine. I have learnt that it is not that simple...

How right you are - there's the JIS (Japanese Industrial Standard), ISO, and JIS Low Profile tapers - and then the possibility of non-standard ones too. This article here on the Sheldon Brown website is enlightening.