Yes, the '72 250 originally had a rubber bulb pump under the pedal. The only electrical function at the pedal was to switch the wipers on while the pedal was depressed. I believe, by the mid-late '70s, Mercedes had switched to electric pumps on most if not all models. The rubber bulb pumps work fine until they get old. Then they either break open or the disintegrating rubber particles inside plug up the washer nozzles. The original Mercedes replacement pumps are expensive but other vintage cars (including some '60s Fords) used similar rubber bulb pumps.
I converted my 250's pump by wiring the pedal wiper-switch to an electric Chevrolet pump.
The pedal no longer works the wiper but I don't mind.

Happy Motoring, Mark

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DrDKW