I have installed many wiper vacuum motors, transmission arms, wiper arms/blades, and on/off switches on 47-53 trucks and I have no idea what you are referring to with "wiper base", "arms", and "tiny flat head screw".
If you could break down your questions into each component, and describe what each piece does, looks like, and where it is located, it will be easier to assist you.
Carl

1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission