Update...maybe. The car's in the shop for valve seals and I had them look into this.

It seems that the foot pump and diaphragm are one unit and still available. $65ish.

__________________
1974 240D "Boldie" 170K.- New timing chain/freshly rebuilt IP/replaced valve seals/injectors/upgraded stereo/new Bilsteins with Yokohamas/fresh paint and rocker panels plus lots of welds.