converting a thomos dudley from mains pressure to tank fed?

[mutley racers]

Well I don't know if I am just being really dumb but there was 2 of us having a go and could not work it out. It seems the fill valve is just 1 piece. When you take the diaphragm out you cannot get to the seating as it is all one piece. Or are we just being daft

 

[chris watkins]

pic's or a link always help mutely.

 

[WHPES]

Probably only for high pressure. Replace the fill valve for a type with the traditional cone seat and replace seat with low pressure version (red).