This flight starts in the same place as the previous flight (so get your IFR clearance to Boeing and set up the radios), but this time your whole vacuum system will fail a few minutes after you start.
Your first solution will be to turn on your standby vacuum pump to restore your AI and HSI. But-sadly-that won't fix it (apparently this was a serious vacuum system failure). So use all the other instruments (especially the GPS and compass) to guide yourself to the ILS.
By the way, even though your HSI stops turning, the yellow CDI needle on it will still show the ILS properly, so you can use it for course guidance; just turn the OBS dial until the needle points up.
Ref.: West, Jeff Van. Microsoft Flight Simulator X For Pilots: Real World Training. Wiley. Kindle Edition(Location 11480).