Tools required:
3mm Allen key
Be sure to use a true metric Allen wrench (aka hex key) - "Standard" (English) fractional wrenches will look similar, but may strip the screw in your grouphead! This will make it extremely difficult to remove. If you look closely, the size and unit will be indicated on the side of the wrench.
Before continuing ensure the machine is switched off and the grouphead is cool to the touch.
Using the 3mm Allen key, remove the dispersion plate and screen from your machine.
NOTE: It is very important to use the correct size 3mm metric Allen key - SAE hex keys (aka Standard or English) may look the same, but are slightly smaller. This can result in stripping the screw head. If in doubt, STOP!
Next, verify the orientation of the dispersion screen (left) and dispersion plate (right). These should be assembled such that the dispersion screen fits nicely within the beveled edge.
NOTE: In these photos, the dispersion plate and shower screen are being held upside down for demonstration purposes. The whole assembly will be flipped together to install the two parts into the machine.Reassemble the grouphead, taking care that the small red o-ring remains in the upper groove underneath the dispersion plate:
See also: