The blower motor is cleverly designed to make replacing the bearings pretty close to impossible. The whole assembly seems to be pressed and welded together, so the bearings, which are the main moving part to wear out, to be replaced.

You CAN lubricate the bearings, which is what makes these things squeak, and replace the brushes without too much difficulty.

You can test it off the car by using a 12v transformer or a battery charger. A test wiring harness can be adapted from wires you snipped off with the connectors attached at the U-Pick junkyard or perhaps scavenged from an old stereo.
I took my motor out, and tested and lubed it, but it won't turn inside the car. I wanted to use the car so I reassembled it and plugged everything in, and it sisn't work. Then the temperature went down to 40º F and it started turning for a brief, though thrilling, period.

I am assuming that I will need to replace the resistor, the aluminum heatsink gizmo that varies the fan speed.

Thanks for posting these photos. It will inspire courage in all of us.

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Semibodacious Transmogrifications a Specialty

1990 300D 2.5 Turbo sedan 171K (Rudolf)
1985 300D Turbo TD Wagon 219K (Remuda)

"Time flies like and arrow, yet fruit flies like a banana"
---Marx (Groucho)