[sc_rufctr]

I wouldn't open the motors. Just get them nice and clean and grease as a appropriate.

I have heard of people opening them up and replacing brushes etc but only do this if they are not working.

With the work you have planned I'm sure they'll perform almost like new.
Just remember these are not modern cable power windows that operate quickly.

I've always liked the "genteel" way the operate. Slow, quiet and classy! (I know I'm strange)