Right, blocked the rear outlet from the pump, and also the return to the reservoir.
Haven't yet swapped out the Hicas rack, but there is Power Steering fluid pissing all over from somewhere or other. I thought it was from the main return to the reservoir, so replaced it with a braided hose, but after taking it for a run out, there's an explosion of fluid all under the engine, hoses, suspension-everywhere.
Is there a possibility that the rear outlet being blocked is causing excess pressure in the system?