Here's a DIY I did for a slightly newer version of the pump you should have fitted to your IP.
Refreshing the fuel pump on an OM617 (European spec – non turbo)
Your's is probably very similar although I think it will have a double / slit cam on the end that goes into the pump.
If you need parts ask the forum sponsors!
EDIT welcome to the forum solarcrete!
EDIT #2 welcome back Alastair where've you been recently?