The 914/4 used the air pressure of the spare tire to pressurize the washer fluid tank. This valve, found in the steering column, regulates the flow of washer fluid when you pull back on the washer lever. A small pin is used to actuate the valve.
Click to view attachment
Note the small differences between the NOS part (with the cap) and the used part. The used part has a hex base for the tubes and a metal bridge tying the tubes together. The metal bridge is loose on the NOS part, so the bridge was not designed for it.
Click to view attachment

This electric switch, which I have designed, is mounted in place of the valve to permit an electric pump solution similar to the 914/6.
Click to view attachment