I did a step by step for fixing those sagging doors. Go check it out.

http://91rsramair.tripod.com/home/id4.html

 

How did you get the roller off? I've got a new one but it looked like there might be some cutting/grinding to get it off. I'd also recommend using the door spring removal tool. I got it online from harbor freight for like $5 plus shipping. It made removing and installing the spring a snap.

 

I used a razor knife to cut the lip og the plastic bushing off and worked the wheel off that way. As far as the spring tool I looked everythere around here and couldnt find one. If I knew thats all it was I wouldve gotten one.