That's a tough fitting to remove - 1/2" BSPP threads with sealer applied. Carefully note the orientation of the boiler fitting - I believe the grouphead outlet is directed straight forward. You will need to remove the fittings leading to the grouphead and the OPV and take the machine to a mechanic's shop equipped with an ADJUSTABLE impact wrench. The size is sorta odd but I believe a 24 mm, six-point socket would work well.



Clean all remments of old sealer from both the male and female threading and replace the fittings using a Loktite thread sealer. I would replace the fitting while the boiler is in the machine to ensure correct rotation.