max and min burner pressure

[desrob]

when testing max and min pressures on gas valve,max is ok but when removing wire from valve to reduce to min and it justs stops at max,am i to assume the potinometer or what ever they are called,is not increasing and decreasing current to gas valve,i got 10 k ohms when slightly warm so ntc not,i got info on altering pot,so i'll give that a go faulty,going back tomorrow any help appreciated.