The shop manual I bought was the two CD digital version and your right about the limited information on 300TE 4Matics. The power steering fluid depletes in about 15 minutes or after driving about 4 or 5 miles. I spoke to the head service mechanic at the local MB dealership and he is concerned about the system(s) fluid contamination. He figured a minimum of 4 hours labor and and a new tandem pump. And that might fix it or at least get them to a point to see what else needs to be done. All the systems will need to be evacuated and bled. He also said that sometimes the gas charged shocks have hydraulic fluid leak into them and may also need work. The leveling system was just rebuilt before I bought it in July and I hope that is not the case. Since the power steering and hydraulic system use different fluids it seem weird that they would mix when a seal goes out. I appreciate your input and would also be more suspicious of the PS unit than the tandem one. I did read about the check valve in the manual. The dealership recommends and will only replace the whole tandem pump because he said other things are probably worn in it too. Thanks again, Paul