The vehicle is a Model W126, Engine 116.965, 420 SEL, 1986.

I'd like to know if it's normal to be able to rotate the distributor rotor by hand with the distributor mounted in the engine and bolted down.

I removed the distributor for changing the water pump and upon reinstallation I was startled to find that I could rotate the rotor by hand without manually rotating the engine. It made me wonder if I broke something.

Another question: The "Service manual CD" instructs that when the distributor is reinstalled it should be aligned as follows:

Position engine to ignition Top-Dead-Center (TDC). Insert and align distributor as follows: "fit on 90 degree angle to notch in the distributor housing edge. Align the markings on distributor rotor and distributor housing very exactly to each other."

I'm having trouble trying to figure out where this 90 degree angle with the notch is measured.

Thanks for any help