Sorry, no diagram for the original post,
but for the 2nd post:
Assuming it was assembled right, it would seem that it would have to be that the shoe adjustor is set too tight, or the cable is too tight.
The shoe adjustor should be rolled back prior to assembly, since the new shoes are likely fatter (less worn) than the old. They are then adjusted for proper clearance after the rotors have been fitted. If the rotors go on hard, the shoes are too tight. On my older model, I believe the adjustor is tweaked through one of the wheel bolt holes (if I remember right- I work on a lot of cars...)
Parking brake cables are generally left alone, unless they were previously adjusted to make up for worn shoes. If the cable is not taught when the brake is released, this is not the problem.
Generally, the adjustors and any moving parts on the actuator lever are pretty frozen up by the time a rear brake job is needed.
A thorough cleaning and lube with moly 'brake grease' usually restores function. Sometimes it's less hassle to simply replace the adjustors, depending upon the design.
Every metal-to-metal sliding surface (including where the shoes rub on the backing plate) should be cleaned, and lightly lubed with brake grease to ensure good lasting results.
Spraying oil into the brake mechanism is a bad idea.
Best of luck.
1986 300E 5-Speed 240k mi.