Please can anyone throw some light on a fault that has developed on my Rocket R58?

When I pull a shot the pressure rises to approx 9 bar and the shot pours as usual but when I move the brew head lever to the fully down position, water is ejected from the bottom of the e61 as normal BUT the brew pressure gauge stays at 5 bar instead of falling to zero as it used to (I'm currently using water tank other than line pressure). The gauge eventually falls to zero but takes a few minutes to do so.

Any help would be greatly appreciated.

Paul

Sounds normal to me. When you lower the lever you close the brew valve. The gauge is reading the pressure trapped between the pump and the brew valve. If you close it quickly, you'll trap a lot of pressure. It will slowly dissipate.
You could move the brew switch further back (by moving its nuts forward on the threaded body) so that the pump shuts sooner in the lever's downward travel, more in advance of the brew valve closing. Additionally you could lower the lever more slowly to increase the pause after the pump stops but before the valve closes.

If it seems really out of whack, perhaps your brew-valve is "muffin-topping" with the rubber valve-face actually deformed and protruding from the brass valve and closing the valve much too early in the lever's travel. Inspecting the valve is as simple as taking the mushroom off of the group head and pulling the valve out. (the big 36mm hex-nut)

Thanks for your help JRising, my memory is clearly playing tricks on me - I was sure it fell back to zero and was worried that the pump was now having to start up against a load. I've just removed the mushroom and the valve face looks ok. Thanks for the tip, one to watch out for in the future.

That's very interesting about lever speed, I'll experiment further.

Again, many thanks, much appreciated!