As I remember, there is not a replaceable PCV valve on the M103 engine, as there are on most engines. Instead, it's just a little orifice that connects the intake manifold with the oil galley on the head - no moving check valve or ball. To clean it, if it clogged, I think you have to remove the intake manifold.
Someone else might check me on this; it's been years since I had the head off and looked at that.

DG