I know this, because many years ago, I planned to tour Kent in my bug. Heading down a quiet, and sunny M40, suddenly I had no power. Coasting to the hard shoulder, I pulled up, walked to an emergency phone (no mobiles in theose days) and than waited for the RAC to arrive. I still see the tree at that spot when I head south to this day.
Once the van arrived, the diagnosis was lack of fuel, and looking at the pump, the pivot in the base was sticking out. Inside, there is a rocker operated by a rod coming out of the engine to bear on one end. The other is connected to the diaphram inside the pump, and that's the bit that moved fuel around.
Back home, I quickly pushed the pivot into place and all was well. But I decided againast continuing the trip.
This was wise, as the same thing happend on the way back from work a few weeks later. Better prepeared, I nipped around the back of the car, shoved the pivot back in and all was well. Which is what I told the very attractive blonde woman who pulled up in a red Beetle to see if all was well. What a time to do a quick fix - she was gone again in a flash, when long chat as I diagnosed the problem would have been very pleasent...
Eventually, I worked out that there should be a circlip on each end of the pivot. Once replaced, the problem never occured again.
The model version is a two-part plastic moulding that snaps together and then pushes into the crank case. I painted it silver (it looks better in real life) and the Bakealite spacer, a rust colour which looks about right.