I removed the entire vacuum pump and disassembled it, cleaned it and reassembled it, replacing the diaphram. The valve/spring mechanism was in good shape, fairly new (about 1 year), I inspected it and reassembled.

The armeture fits against a circulating cam, as you know. Lucky or not, I have never had an issue replacing it with the orientation of the cam relative to the armeture inside the vacuum pump. It is flush when it comes off and flush when it goes on.

You are right, it could be another reason for the failure, however, my experience is that when the oil gauge flutters, I have now power breaks and the car won't shut off, it is the diaphram.

JCD