[zzyzzx]

Before you go through all of the time and hassle of swapping motors and regulators, try just replacing the switch.

When I did it I unplugged the motor from the harness and manually powered it and it worked just as bad. That's how I tested it. The new one has worked perfectly ever since. There cars have crappy window motors from the factory.

 

[zzyzzx]

few people have access to a suitable 12v power supply

There is usually one of these nearby, already in the car:

 

[zzyzzx]

Why do suggest to change the regulator and motor as a pair? Do you mind, sharing your insights?

Check pricing on a motor/regulator vs just a motor, and the answer will be self-explanatory.

 

[zzyzzx]

I have no real idea how to pull my power window motor out of the door and hook it up to the battery directly.

You don't have to remove it to test it. That's what extra pieces of wires are for, along with there things: