Early 93 USA Vanden Plas 671330 brake boost not switching on

Early 93 USA Vanden Plas 671330 brake boost not switching on
I can jumper the ABS relay and the pump turns on.
The pressure switch shows continuity at low/no pressure between pins LS2-1 WN and LS2-4 YP.
Reservoir full
Brake hazard light is on
ABS light is on

Does this suggest Combined Pressure Switch failure or ABS module failure?

How does the ABS board come out of the housing seeing as all 6 torx screws are removed but it doesn’t want to budge?

Certainly suggests to me that the combined switch has failed, when mine failed on my early 2.9 I removed the cover of the relay under the knee pad (RHD) and would manually close the contacts to fire up the pump.