Testing Round 1 (not much time):
I can hand crank it fairly easily now, it does seem to get a little notchy in places.
Also the starter can turn the engine over however I have to hand crank it a few time first.
I did noticed the oil pressure went really high after a few turns of the starter
Testing Round 2 (a bit more time):
Thermostat is fine, water pump seems to be pumping OK, but not pull it out yet (rad is in the way). Oil in the bottom was quite dark but not clumpy. Oil in the top was still quite light.
When you crank the engine on the starter a few seconds the oil pressure goes way way up – I stopped at 6 bar.
So me thinks there’s a blockage somewhere. Not pulled the sump off yet, but that’s the next step.