BMW tire pump

Hello; I tried to repair a flat on my mountain bike, couldn't find my 10$ lighter socket plug in compressor. I had my granddaughters favorite ball to repair. I had been servicing my R100/7 and had noticed teh pump under the seat on the left side.

It took me awhile to figure out how to work it, it had to be held pretty still to keep it from leaking air and wasting effort. Filling the ball was an endurance test, each stroke would only put in about a teaspoon of air.

I used it to make the tube round, but any attempt to raise any pressure was hopeless. I took it to the gas station, seems to be holding.

Has anyone found a way to make it work?

When new, they do work, albeit slowly. I have used a newish one to pump up the tire on my /2 after repairing a flat. It was tiresome ;-) but it did work.

There's a seal inside, and yours may be dead. I'm not sure if parts are available separately, although I do know that the pump can easily be disassembled for inspection.