It sounds a lot like this
foot operated windscreen washer, that was sold by Nasco.
Another thing to note with the vacuum wipers is that there are two different petrol pumps, the early FE type which only draws vacuum from one of the two chambers, and the later FE/FC type with 4 valves that uses both sides of the diaphragm to generate vacuum. If you buy a kit from Rares (or elsewhere), make sure you get 4 valves if that's what your pump requires.
The early type is completely useless, as opposed to the marginal efficacy of the later type, once they start to get old.
As someone else mentioned, check the rubber line from the pump to the wiper motor. If it's developed angina, replace it - that can make a significant difference.
cheers
RET