I would be interested to know the relationship between the vacuum pump and the altimeter. More quality journalism!!!
This was a sad and needless accident and one I shall be using as a case study to re-affirm the importance of aeronautical decision, for an instructor seminar I will be running in a few months. Flying on a partial panel is something I have practiced since this incident, to a point where I can now comfortably shoot an unfamiliar NPA on pressure instruments alone. If you are not comfortable doing this and do not have a secondary AI then you really don't have too much business going into IMC in the first place.
And one final thought - The AI/DI should be regularly cross checked against the pressure instruments to ensure they are in agreement with each other. Gyros tend to topple quite slowly - check them against ASI, altimeter and compass.
RIX