W124 300CE Seat Lock

[optimizer]

Hi there -

Both the front seats recently stopped locking in my 300CE. I looked underneath at all the vacuum pipes and didn't feel / hear any leaks.

The MB shop diagram says that it gets its vacuum from the intake manifold, but I couldn't figure out exactly where and if I should be looking for a hose that was maybe disconnected or something (I recently did a valve cover gasket replacement and a few other minor things).

Any help tracking down the source of the vacuum would be helpful!