You are preaching to the converted, AndyRR.
I did say, earlier in this thread, that the better approach to this issue would be to ascertain facts and cause...
I was hoping, perhaps as an act of purest optimism, that given the number of these engines that are being run out there, someone in pprune land would have some basic tech data on basic parameters such where the carburettor/induction system is designed and tested to put the cylinders on the lean curve.
The existence of a modification permitting manual leaning suggests that someone is playing with this stuff and may have some useful data.