Thanks to Onefunkyman for this very useful topic. I have just got round to chipping my Caerphilly Castle, (having kept in the box for a couple of years) only to find that Railmaster can't read the CVs. I too had run it in successfully on DC before hand.
Thanks also to Matt Roe for the hint about disassembling the plug with the aid of a scalpal. This meant that the fix was quite straight forward which has saved me a lot of faff trying to contact the manufacturer.
With regards to the quality control at the manufacturer, I wonder if the Caerphilly Caste batch may have been on the whole poor - my tender would not come apart because the cab end hand rails was glued to the chassis and when I was finally able to prise it apart the water tank filler flap fell off - is this what is meant by "Special Edition"?
Alas Onefunkyman's sentiments about boycotting the products whilst understandable may be in vain, I have also tried chipping another manufacturer's GWR ROD 3000 2-8-0, which showed the same symptoms - not reading CVs in program mode. A trial in normal mode using the default address resulted in blue smoke and a short circuit....