Just returned from a brilliant week at Kelling Heath. 7 good nights out of 7 - amazing for the UK!
The eFinder got a good shake down and is now working extremely well. Achieved pointing accuracies with respect to actual sky (J2021.3) is 1-2 arc minutes.
Bentley Ousley in Kansas has contacted me as he was trying to make a similar finder but was stuck on the code. We worked together with me producng a new version for his ServoCat driven 20” New Moon scope, and he made me a 3D printed 72mm f2.7 finder scope.
By now I had also abandoned the Raspberry PI HQ ccd (pixels too small) in favour of an ASI120mm-S mono ccd. This ccd with the f2.7 guide scope produces excellent images with just 1 second exposures.