Quick Update seeing as I can no longer edit previous post: No joy with the engine, however very happy with the 0.7mm annealed aluminium washer between the spinner pack plate and prop driver. The washer has confirmed to the spinner backplate knurl and it's seems fairly stuck there, and the knurl pattern of the prop driver in the washer is very neat and crisp indicating no slippage despite 2 hrs of (wildly at times) random forces currently being transmitted to the prop.

Impression from the prop driver is neat and crisp.