You should change the gasket on your espresso machineís group head every year or so, along with the shower screen. Most cafes will switch out their gaskets, portafilter baskets and screens roughly every quarter. Home use doesnít put so much wear on those parts, but an annual routine will ensure a well-functioning espresso machine.
If your machine starts dripping water around the outside of the portafilter during brewing or if it becomes difficult to lock the portafilter tight enough to create a good seal, itís time to change your group head gasket. The gasket is secured around the outside of the dispersion screen and the pair is installed in a circular groove in the group.
The Steps :: Screw Mount
Loosen the screw in the shower screen and remove the screen and the brass plate in order to gain easier access to the gasket. A dispersion washer will also come off with the screw, screen and plate; be sure to keep all these parts in the proper order and orientation for reassembly. Be aware that these parts will be very hot if the machine was recently on.
Use a pick, awl or flathead screwdriver to pry the gasket out of the group head. This may take some effort and an older gasket may come out in pieces. Make sure that you donít leave behind any part of the old gasket.
With your new gasket ready, place it into the cavity in the group head with any logos or lettering facing up. Push it up as far as you can around all sides. If you canít get it all the way in, donít worry; weíll take care of that in a few steps.
Replace the brass plate, dispersion washer and the screen into the group head, tightening the screw with your fingers as much as possible.
With the screen back in place and the gasket in as far as you can get it, engage the portafilter and crank it over so that it pushes the gasket the rest of the way in.
The Steps :: E-61 Mount
Looking up into your group head, use an awl or pick to pry the gasket from the groove, removing it little by little around the circumference. When the gasket is free, the screen will come out as well.
If youíre not replacing the screen, take this opportunity to thoroughly clean it, soaking in a solution of Full Circle if necessary.
To install the new gasket, push it around the outside walls of the screen with the beveled edge of the gasket facing up and the screen facing down.
Lock the portafilter in the group head. As you tighten the handle into the group, the gasket should fit tightly into the groove. If the previous gasket was excessively worn, youíll notice that the portafilter feels much tighter in the group head and wonít turn as far to the right.