I'm doing a head gasket on my '93 300D and am currently ready to install the camshaft. I seem to be missing a little part, in the EPC parts catalog it is called a "Fixing Lock" which looks like half a washer. It sits in the head in a little slot. Well it seems mine disappeared while cleaning the head. I can't find it anywhere. In the FSM diagram it is called a camshaft lock washer. I'm pretty sure it was there when I pulled everything apart but it has disappeared.

Problem is, I can't seem to locate a replacement anywhere. The part number seems to be 601 051 00 73. Any ideas where I can get this little thing?