Has anyone ever fixed this and could you please possibly give me a clue as to where to start? Both of my doors are like this...

 

It is called the 'window belt weather strip'

It comes off and you put a new one on, there is of course a left hand and right hand side, so get the correct side.
Can't remember if it has a screw or clip on the ends or just pops in and out.

Example here: RH Side Front Door Exterior Window Belt Weatherstrip 1999 2011 Ford Ranger | eBay

 

I see. I'll be looking into this. Thanks for the info, much appreciated!

 

There was someone that removed the OEM finish and repainted the pieces... I've been wanting to do that, but laziness kicks in.

 

You can order it online from JC Whitney.