valliant turbomax

My boiler is Valliant turbomax plus 828 /2E I want to re-pressurise the system but the head on two flat head screws that I would turn has crumbled and I now need to replace. What please is the part (I believe it’s a filling valve)? Also are the easy to remove and replace? Any guides on how...

Hi Folks, Being a long time "sufferer" of the elusive Turbomax F22 Fault I've set up an account here just to post my as of yet seemingly un-published fix! Posting it here because over the years this site keeps popping up as the closest anyone's got to suggesting but rarely completely resolving...