Just in case your interested, the modern technique for locating vacuum leaks is the use of a "smoke machine".
This device applies 1psi of a very dense smoke into the chamber to be tested. It quickly indentifies the leak. I have even heard of people using it to find door lock vacuum leaks and evaporative systems leaks (common fuel smells).
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician