During the early days of Beverley flight testing at Boscombe Down I used to be continually frustrated with engine starting. It seemed impossible to home in on the correct priming for those monster engines and there was much time spent overheating the long suffering starter motors.
We didn't sort the starting problem out in my time at BD.
The other persistent problem was failures of the electrical brush housings for control of the the props.
Did these problems persist in service?