By " maintenance set" ..... what does that mean ?
The 240d engine for instance has an engine manual and it has a maintenance manual ( which includes other models).... so is the latter what you mean that you have?.....
Trouble shooting... as with lists and perhaps flow chart diagrams exist for diesels in general.... these are pretty standard engines with regards to the oil pressure system..... there are notes in the books .... for instance a note to check and replace the oil pressure valve screwed into the oil pump if there is a sudden loss of oil pressure ( particular on an engine which has recently been apart )...
It might be better to state what YOUR oil pressure problem manifests itself as with regards to symptoms... and see what people come up with...
Have you done a search on the forum for this ? Lots of stuff is already there...