srobinson wrote:With the group head now off, it is time to remove the plunger and the group head screen. Please note...DO NOT USE A SCREWDRIVER! Damage can occur. The best way to do this is to invert the group head and carefully press the threaded stem until the basket breaks free of the group head gasket.
I agree that you don't want to use a screwdriver here. But when I tried to 'carefully press' to free up the portafilter gasket and screen, it wasn't yielding. Fortunately on one of those days when I visited Christopher Cara, I saw him servicing a grouphead as his father had taught him to do. He removes the dipper tube and then mounts the grouphead upside down on the machine like this. The rest is my improvisation. I used a picking tool to remove the portafilter gasket and shower screen. Both came out easily without damaging anything.
Then I removed the grouphead from the machine, pressed the top of the piston shaft onto the wooden workbench, and it came out easily. Removing the dipper tube isn't hard. It's threaded and turns out counterclockwise.
Removing the piston gaskets from the brass piston is easy using the picking tool, something I've also seen Christopher do with very old, stiff gaskets.
I'd recently acquired this machine and knew it was time to service the group when it would dribble on warm-up. But I was confused by the 'lever erectus' where the lever raises as the machine cools, suggesting a tight seal in the piston gaskets. Someone on another thread had suggested there were coffee grinds interfering with an otherwise tight seal, but that wasn't the case. So the gaskets were past their prime and would create a tight seal only when heated.
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