Another twist in the saga....Not coconuts and not engines, drives, couplers or clutches either. It was the gauge!!!
Yep, we had to go for about an hour before the fault came. With the PC connected to the engine is was showing 3200 RPM whilst the gauge was showing 6000 RPM! In my attempt to bring the RPM down previously in fact it was taking the RPM down too low hence why I thought there was a power drop

So off to the broker to get the gauges replaced.
Tune in next week........