Potential Pressure Problem - new Expobar lever
I am new to coffeesnobs and a new espresso machine owner. I have had my H/E expobar lever for a week and a half and am loving the coffee's from it.
In the last couple of days, I have noticed a change in the behaviour of the pressure, and am wondering if it is a problem...it still seems to make great coffee.
I switch the machine on...it builds pressure to about 9 bar quite quickly. I then pull my first shot...still all good. However, it seems that when I remove the portafilter and flush water through the grouphead, the pressure quickly drops down to about 2 bar. It then seems to hover between 2 bar and 4 bar until I pull another shot, when it reaches 9 bar while extracting, only to drop to 2 - 4 again afterwards....
Is this likely to be a problem ?