Auto Focus with Meade SN

I’m keen to hear if any other SGP users are having success with SGP with Meade Schmidt Newtonian optics. I’m finding it quite difficult to achieve reproducible results and the autofocus routine ends up at a different optimal focus point to the Bahtinov mask. I’ve been through a reasonably rigorous process to eliminate focuser backlash by putting a dial gauge on the focuser to check for clutch slip and backlash so I don’t believe this is the issue. I’m also finding the V-curves are very flat near the focus point (possible small critical focus zone due to f4?) and the slope of the V-curve is different inside/outside focus. I’ve been extracting the focus curve data from the log file and comparing this to CCDIS FWHM values and in some cases the results compare well but not in all cases.