I see in the hewland manual the reference for the SK681 setting jig, or the alternative style listed on Primus. It appears both are a means to reference the carrier centreline to some known fixed dimension from which to measure the gap "Y" on diagram to set pinion depth.
In the diagram posted below, does anyone know what the dimension I have drawn on, labelled "Z" would be?
Long story short, changing ring/pinion and won't have time to get the setting jig delivered, but have access to machine shop and considering making our own fixture to reference off of carrier centreline.