Here is JimF's site info on the Oil Tube issue:
Also, here is the TSB on this issue.
Engine - Valve Train Noise, Low Oil Pressure
TO: ALL DEALER SERVICE MANAGERS
ALL DEALER PARTS MANAGERS
CC: MBNA FIELD PERSONNEL
VPC / PDC MANAGERS
GROUP 18 - ENGINE M119
In case of complaints of ticking noise from the valve area and/or low oil pressure, the cause could be a missing plug in the oil feed tube (part no. 119 180 02 66) between the camshafts. If one of these plugs is missing, the oil pressure to the valve elements / chain tensioner will drop causing this complaint.
The complaint can be repaired by exchanging the leaking oil pipe and checking if all other plugs are tight. The loose plug can usually be found in the valve area or in the oil pan, and should be removed.
After the repair, start the engine and check the oil pressure. The oil pressure must be within specifications (< approx. 6 Bar). Oil pressure which is too high can be the result of a faulty oil pressure relief valve (See Diagnostic Directory 18-121) which in turn can cause these plugs to be pushed out. If the oil pressure is found to be too high, please proceed as outlined in "Remedy" of Diagnostic Directory 18-121.