As with any espresso machine, the primary cause of leaks is limescale buildup on a fitting or part, which then malfunctions. The OPV can leak if it stuck open with limescale or particles. The internal spring (not sold separately) can be compromised, as well. One can try to descale the grouphead only with a blind disc in the portafilter. Please make sure to remove any water treatments from the reservoir.
(Check to make sure this part if it goes to the reservoir or the drip tray and look for any leakage)
Some have tried to take the ends apart and descale the internal pieces with success. However, the success rate is low once limescale has impacted this part.
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