I posted a couple of questions about the vacuum leak problem with my 76 240D's central locking and got some helpful replies. Since then I've found some very helpful people who do all kinds of things for Merc owners, including the writing and publication of repair manuals for the jobs they get the most questions on, such as central locking. There are others too. Thought it might be of some use so here's the details: http://www.**************.com

If you're in the US you can call the very helpful Kaia toll free Monday to Friday 9-5:00 PT on 1-800-513-5797.