Removing vacuum pump

[deanyel]

Car is a 92 400E. I'm trying to take out the central locking vacuum pump under the back seat. The vacuum hoses come into a sort of manifold, black plastic, that attaches to the pump. It looks like the pump can be removed by just detaching this manifold, so the hoses don't have to be detached individually. But the manifold doesn't seem to just pull off. There is a hole and a little grooved tab but I can't figure out how it works and fear I'm going to break something, again. Does anyone know how this works? Picture below. Thanks.