Ah that makes sense. I suspected I was being a bit optimistic that the GA250 would be a plug and play solution...

Hopefully a new set of wheels with some more grip will make the straight line thing come a bit more naturally, but I have picked up one of the Drift car gyros just to experiment with, as they're currently only £11 from HK which is quite a bargain. Even if it's no real use for the current robot it will probably come in handy one day...

Cheers for your help!