Fitted the new part and it seems to be running OK now. I now reckon that the car had the wrong part fitted to start with. Although the new one fits to the pipes, the bracket to hold it to the chassis is bigger than the unit, indicating that maybe the the one supplied by G&S was correct after all (it was a bigger unit). This may also explain the early failure of the last accumulator (after 70 miles) as it may not be man enough for the job, so I'll have to keep an eye on things.
