Check if the Ace/Hydraulic pump is working...

Yeah, I think they can all be replaced, but I don't know how you'd find out which one? Could just be a connection issues, there's tons of small wires there. I cleaned it once and it was full of dirt and sludge which gets trapped in there...

Ah great thanks - Is there a way to check the pump on the side of the engine? Presume where the belt is and where the silicone hose goes into from the resevoir.

Just find it strange it worked for 2 days after I swapped the pipe with no issues :/