This is an "is it normal" question...

I just realized that when performing a backflush session, the rotary pump pressure on my Pro 700 would rise from its normal 9 bar setting up to about 12 bars. Pressure may have crept up before that but I really noticed the needle going all the way to 12 bars during a normal extraction after a backflush.

I'm going to set the pump pressure back to 9 bars using the adjustment screw, but I'm wondering if operating the machine blind (either with a blind filter or with a very dense puck) will naturally mis-adjust the pump pressure setting. I just hope this is the case and the back pressure itself is enough to slowly set the pump to a higher pressure. My fear is that somehow I keep setting the pressure lower on the screw and run out of adjustment room at some point.

Perhaps the backflush clears some residue out and allows more water to exert pressure too, but it's the second time I have to set the pressure lower: I've never had to set the pressure higher. Maybe residue buildup makes the pump work harder to reach 9 bars and when they're cleared up the pump pressure is out of whack?

After adjusting the pump pressure are you locking the adjusting screw with the lock nut?

*blank stare*

I don't think there's an easily accessible lock nut on the Pro 700. Which is perhaps part of the problem.

Looking at my profitec from underneath I don't see a lock nut. I think I do remember seeing one positioned a bit higher from the screw when I removed the casing on mine a while ago.

The lock nut is inboard of the face of the screw on the pump along the threaded shaft, many of the machines with a externally adjustable pump pressure access hole do not give you access to the lock nut or even let you see it....so the hole is a bit mute.

Specifically the nut is tightened up against the housing of the pump, so unless you can see all the way to the pump housing, you won't see it.

Look at this picture

Thanks a lot guys for pointing out this lock nut. I'll try to adjust pump pressure and tighten the lock nut as soon as possible.