Can I adjust a pressure release valve by myself without any professional assistance?

Yes, it is possible, but please make sure that you take off the non-movable handle, drain the system, take away the rubber tank. You should not drain the pump, but you will have to disassemble some parts of it. Moreover, the correct adjustment of the pressure release valve demands particular experience and skills. Therefore, it is better to trust the adjustment to the professionals from the Service Center.