Its not an electrical thing. It seems to be down to the starter cog / ring gear. After 2 grinds, it turned over after I rocked it in gear. Damned frustrating.
Yesterday I spoke to the mechanic who changed the clutch / flywheel (to a solid) 8kmiles ago, he said that there is a different number of teeth on the solid flywheel compared to a dual mass type. Hence a different starter cog. That's about the only thing that seems to make sense these days.
This suggestion was ridiculed by the starter motor supplier.
Can any one vouch for the number of teeth matching / varying between the solid / dual mass types?
Getting desperate now.