Thanks both (Edward and Kevin) for your helpful responses.
I can only imagine that the Colour Palettes had been manually updated previously by others - I'm not sure how to do this. Presumably, if we used the current library personality, everything should be fine? From memory, beam/effects parameters were problematic too, but this was only after re-creating the Automatic Colour Palettes following importing the P36 and ColorSource personalities, which makes sense.
Looks like we'll need to bite the bullet and upgrade to 7.13.
The Colorsource spot and Intimidator personalities are included in the latest library and I can import the Performer 36 from the legacy library.
I'm guessing that upgrading will require full re-patch?
Thanks
Mike