MediumRoastSteam @DavecUK I answered this above:
“I do have a group mounted pressure gauge. I have three positions - fully down, middle without pump activated, an fully up with the pump activated. Machine gauge rises to 9.5, flow gauge stays at 0.”
Flow control gauge only shows pressure if there is a blind filter or puck under it, or if the flow control is closed.
If you think this might be a faulty pump, I will keep an ear (and eye on that) - the problen did not duplicate itself again this morning, so hopefully this was an anomaly that has passed.
Edit - to further clarify, when the problem occurrs, the group gauge just stalls at whatever resting pressure it is at - either zero or sometimes 2 bar.