The servo is not the current prime suspect. The brakes do not feel unassisted. They feel like they need bleeding or adjustment. They are spongey, and only firm up on the second or third pump. They do stop the truck, but feel alarming when first used. There are discs on the front, but the brakes feel like old Landy drum brakes that need their shoes to be looked at.
My mobile mech is busy, so I am just off to a local Landy specialist to see if he has time to do the brakes.