The service manual (there are different ones for each module) are not much help unless you already have decades of practical service experience working on the exact model and specific module. A vac leak could be caused by hundreds of things and to troubleshoot it you will first need to rule out what is NOT causing it. First, make sure the person doing the troubleshooting has years of experience with this type of instrumentation (both as a user and ideally as a service engineer, or equiv). Next, check the various instrument logs. They will often list line by line specific errors which can tell you where the error was detected. Verify what works by checking the individual pumps and systems, offline if possible, to verify instrument operation (sim to an IQ).

BTW: If this was an instrument which was used at your facility, then put in suspended animation for awhile, then restarted, it should not be difficult with the right people, skills and procedures. If you are describing an auction purchased system (as is common these days), then assume nothing works and start at the beginning by running individual checks (IQ and PV) on everything. Most of the auction purchased systems were sold off because they were broken/contaminated and can be very time ($$$$) consuming to recover. 

I disagree with Bill; the service engineers at Agilent rarely have decades of experience. Typically you're lucky if you get someone with a few years of experience. The manuals are actually quite good. I've been able to diagnose and fix my 1946D several times. I'm happy to send you what I have from a manuals standpoint if you'll send me your e-mail address (I have them in PDF format). 

If you happen to be in the market for a good used 1946D I am selling mine. It's been running fine. We have moved into using exclusively tandem systems for our work, but mine is very sensitive and quite stable for a single quad system.

Mark, I do not recall ever suggesting he find an AGILENT service engineer to work on his older LC/MS system. While Agilent does have some engineers that have been with the company for decades, I suggested anyone with the right experience. There is no replacement for practical experience when troubleshooting these systems. The right person can usually figure out what needs to be done in a day vs a poorly trained engineer or user who may take months to work it out. My point was and still is that: TIME is MONEY.

I also do not recommend to any of my clients that they invest in the purchase of any of the early 1946-series modules. Better systems are available.

Thank-you for your comments. We are tracking down the vacuum leak. Service manuals are always great to have available. "Back in the day", we had these manuals available for all of our instruments.

I am looking for the same manuals, if someone is willing to send them, please message me.