I have a Bombas ITUR F3 pump with a pressure control valve on top.  Pressure reads between 6 & 7 bar which I now understand is far too high.  If I remove the domed plastic top of the controller will I find adjusters underneath? My query is - is it safe to remove this top or is there some enormous spring contraption there which will bite my hand off?  If safe,  then guidance will be appreciated to get down to a more reasonable 3 bars.  Many tks in antic.  Cannot find anything via Google.