I don't know of anyone with an old Mercedes that doesn't own a manual from Mercedes Source. I have a 80' 300SD (w116) that I inherited from my father, and while it may be a work in progress, I use it as my daily commuter. It helps that I work 6 miles from home.
I generally check chain stretch when I have the valve cover off. This involves aligning marks on the camshaft with the cam tower and then reading stretch off the crankshaft timing marks. Precise alignment of the cam marks is difficult so I usually repeat the measurement several times, each after a complete cam rotation (always in the right direction).
That's good that you know how to do that it's very important to change the power steering fluid and filter. The power steering fluid filter is one of the most neglected items on these cars.
